My Kingdom Come
by Madfizz
Summary: The Doctor may be the last of the Time Lords, but that won't stop another dwindling species from having their 'purrfect' revenge. Post-Last Christmas and Pre-Series 9. Tried to write it like a typical episode...
1. Hallucination

_**Chapter 1**_

"Hello?"

"Clara?" the Doctor asked with curiosity thick in his voice, even over the static of the phone. She held her breath, waiting for him to continue. "Something the matter? You rarely call…"

"Uh, yeah actually. Doctor, I'm afr-afraid I won't be able to travel for a bit. I'm sort of-" She trailed off, too embarrassed to finish the sentence. "Wait, where are you? And why is the connection weak?" She could only hear faint white noise before the crackle of his Scottish accent broke the silence.

"Doesn't matter. I'm headed to you right now. Stay where you are, I'll be there before you can blink. On second thought, don't blink. You know, if you're under attack by weeping angels." The Doctor rambled.

"No, no. Doctor, it's…" Clara started before the line cut out. Even after the Doctor hung up, Clara could still hear the tinge of worry in his voice. _Well that's not how I was expecting that conversation to go,_ Clara sighed deeply. She glanced around at her surroundings, wondering why her room was predominately white. The afternoon glare of the sun pierced through the only window in the room, painting a bit of those white walls in a brilliant orange. It was nearing sundown now, and it had only been an hour or so since she was transported from Coal Hill Secondary School to the hospital. During that time, she had debated on whether or not to call the Time Lord and inform him of her current condition. She stared at the concrete ceiling, dreading the weeks to come.

The wheezing of the TARDIS broke her out of her sombre trance. She brought her left hand up to cover part of her now reddening face, immediately regretting the call. Seconds after it had materialised, The Doctor burst through the doors of the bright blue box. He ran over to her bedside, brandishing his sonic screwdriver and frantically scanning every part of her being.

"Doctor," Clara began. He ignored her as the sonic finally made its way to her untreated right arm, which was placed carefully on a flimsy sling. The device made a small squeak, relaying the data to a now confused Time Lord. "As I was trying to tell you over the phone, it's nothing. It's just…"

"A broken arm." He finished. Realisation and relief washed over his face. Clara watched his eyebrows knit together, then gazed into his sharp blue eyes. She could practically feel more blood rush to her cheeks from his massive fuss.

"A broken arm. I'm about to head in for surgery now to get it fixed up. That's why I won't be able to travel with you for at least a few weeks." Clara explained quickly, before averting her eyes away from his. He stood motionless beside the bed for a few moments, prompting Clara to shift awkwardly from her sitting position.

"It's also your wrist. It's a clean snap, but that's beside the point." The man finally said. He started to pace around the bed slowly, sheathing the sonic as he did. "Clara, I thought something serious had happened. This is not a time to be making prank calls".

"This _is_ serious though! I won't be able to write, let alone go to work for the next couple of weeks. I won't be able to travel with you either!" Clara exclaimed in disbelief. He snorted, continuing his restless pace. "Look, sorry that it sounded like life or death to you. I was just a bit embarrassed, that's all. Not my fault you jumped the gun either!" The Doctor's eyebrows arched slightly as he turned to her, coming to a halt at the foot of her bed.

"How'd you do it then?" He asked, nodding towards her aching arm. He leaned over the bedframe, clasping his hands together expectantly.

"Er, I uh. I fell."

"You fell?"

"Yeah, upwards actually. Upstairs, I mean. I fell up the stairs at Coal Hill." Clara muttered, avoiding his now disappointed gaze. "What else were you expecting? A surprise alien invasion, thwarted by yours truly, with only a broken arm to show for it?" The Doctor chuckled, leaning further over the metal bedpost and causing a slow creaking sound. He seemed a lot more relaxed now, thankfully.

"I'm glad this wasn't serious. Please though, in future, don't scare me like that. I'm well over 2000 years old now, I'm getting on…" he explained. Her eyes ventured back to the well-dressed figure at the end of her bed. His slender fingers now fiddling with the sleeve of his Crombie coat. He'd ditched the vest and white shirt in favour of a dark purple collar shirt today. "So, should I be asking what the other guy looks like then?" he mused.

"It's not funny, this." Clara warned, eyeing his now widening grin. She could tell that he wouldn't let her forget this.

"Clara Oswald. Bested by stairs. You know, you could ha-"

"I knew you'd find this hilarious. That's why I was so hesitant to explain on the phone!" Clara cut in dejectedly. She slumped further into the bed a little too quickly. The movement caused a sharp pain to coruscate through her arm. She winced as she stopped herself from allowing her left arm to grasp the other. The Doctor's grin faded instantly, his eyes darting from her eyes to her arm. He pushed off the bedpost and strolled back to the TARDIS, then turned on his heel to address Clara.

"I won't fix the bruising. Not just yet. Don't want to scare the pudding brains now, do we? I'll tend to it after the surgery." The Doctor explained. Clara watched as he turned back to the TARDIS. She opened her mouth to ask another question, but the Doctor had already sensed what she was going to ask. "It doesn't do bones, unfortunately." He added, hovering by the TARDIS doors and idly waiting for some sort of response.

Clara sighed. "Come back in an hour. I'll be out of the operating theatre then. Not sure when they'll let me out though. Probably when the anaesthetic wears off."

"Oi, what have I told you about the eyes? Don't worry about the 'being bored out of your brains' thing. I'll take you to one of the best medical facilities on New Earth. They'll cut down your recovery time to a couple days." He waved his hands about nonchalantly, disappearing through the doorway.

"But, but I can't turn up to the school good as new in just a couple days!" she stammered after him, throwing her left arm onto the bed to add dramatic effect. He poked his head out of the TARDIS, a mischievous grin plastered onto his face.

"Who said anything about going back early?" He insinuated. He gave, what Clara made out to be, a wink before disappearing into the TARDIS. Clara watched as the TARDIS dematerialised, the whirring of the ship fading and leaving her to her thoughts. _He has most definitely played hooky at school then._ She smiled; perhaps these coming weeks will be alright after all. A nurse came into the room, interrupting her thoughts.

"Miss Oswald, are you ready to go?"

XXX

Clara struggled to open her eyes. She attempted to lift herself out of bed, but to no avail. Her limbs would not cooperate. Through her blurry vision, she forced her half open eyes to venture on without her body. There were a row of gurneys lined up on each side of the quiet room. Each had motionless occupants, with only two nurses milling about. Clara figured that she was at the end of the row, closest to the exit. Deciding that there was nothing interesting to see, Clara opted on going back to sleep. Out of the corner of her eye however, she could have sworn that she saw a third nurse leaving her bedside, making her way for the exit. Clara watched as she hurriedly pushed through the doors, glancing back as she did. Clara caught a glimpse at her face. It was unmistakable - a surreal sight. Or was it her blurry vision? _Did that nurse have whiskers and grey fur?_ She giggled at the thought, then allowed the recovery wing to fade away into darkness.

XXX

"Clara, Clara, Clara. Sleeping in is starting to become a habit of yours I see." The Doctor quipped, watching with an amused expression as the woman came back to the conscious world. Moonlight broke through the blinds, lighting up the shadowy hospital room. This prompted Clara to blink rapidly in awe.

"It's night? That wasn't an hour, was it?" Clara asked wearily. The Doctor chuckled in his chair. Some of his features were highlighted with the pale moonlight. If it was anyone else viewing him, it would have been an eerie sight indeed.

"Well as far as I'm aware, that's what happens when time passes on Earth… And, it was two hours or so." The Doctor answered cheekily. He rose from the chair and strode over to Clara's bedside. Clara checked the clock on her bedside table while the Doctor equipped his sonic screwdriver and ran it over her numb right arm. She could feel a strange tingling over her skin from underneath the cast.

"Ten past six. Wow, where did the day go?" Clara muttered to herself. The sonic stopped humming, and was promptly pocketed by the Doctor.

"Bruising's gone. Now for the fun part," The Doctor beckoned her to come with him. "C'mon, you haven't got all night."

"Where's the TARDIS?"

"Roof."

"Why?"

Clara could practically feel his eyes bore into the back of her skull as she got out of bed.

"Because, Clara, I couldn't very well materialise into the room when there were nurses in here now, could I?" The Doctor explained, "Besides, the walk will do you good."

"That didn't stop you earlier!" Clara retorted. She rummaged around her bag to find the clothes that she'd worn before having to change into a hospital gown. After pulling out her outfit - which consisted of black jeans, converse and a sweater - she entered the small bathroom to change. The only noise she could hear was a grumpy old man's grumbling and muttering from within the room - something about being tricked and whatnot. Other than that, it was quiet. _A bit too quiet for my liking,_ Clara thought.

The pair made their way through the 5th floor corridor in silence. The Doctor led Clara to the lifts, babbling about the place they were headed to. Normally, Clara would've partially listened. But this time, she'd tuned out. Instead, her mind drifted to the recovery wing…

"Anyway, we can't access the highest floor with the lift. We'll need to take the lift to the 6th floor, then go up two flights of stairs to the roof. Now, I know what you're thinking. Stairs are a no-no right now, but I'll protect you. I -"

"Wait, why not to the 7th floor?" Clara piped in. "And, shut up!"

"Construction on the west wing is preventing the lift from going to that floor unfortunately." He dismissed, flicking his hand to point above them where the construction was. Clara had to supress a groan in fear of being taunted more. They rounded a corner, spotting the elevator at the end of the corridor. Realising that they wouldn't be able to have a private conversation once inside the lift, Clara debated vigorously with herself whether to inform her friend about the peculiar sighting in the recovery ward. Various thoughts came trickling through. _He's going to roll his eyes at me since I 'tricked' him last time I tried to tell him something important. How utterly ridiculous would I sound? No, let him know. I've seen stranger…_ The Doctor gave a sideways glance at Clara, noticing her furrowed brows and slowing pace.

"Now what's wrong?" he inquired irritably. They both stopped a little ways before the lift. Clara watched as a nurse wandered past them. She took it as an encouraging sign to silence her thoughts once and for all.

"Doctor, is it common for someone to… er, have a hallucination while on anaesthetic?" she tapped her chin nervously with her fingers. The Doctor quirked an eyebrow.

"There have been cases, yes." The Doctor nodded. He tilted his head slightly in anticipation for Clara to continue.

"Well, it's just that I've been on anaesthetic a couple times before and… It's never happened. Also," Clara paused, taking in a deep breath. "Lately it's been a bit hard to tell, you know…"

"To tell what?"

"What's real and what's not." she breathed quietly. The Doctor noticed that she'd brought her hand down from her face to intertwine it with the casted hand. She was fidgeting.

He felt his hearts twinge slightly.

"Oh." was all he could manage. They hadn't really discussed the events of Christmas 2014; they'd distracted themselves with their travels. A month had passed since then, but he very well knew that the damage was done and was far from healed. Truth be told, even he had his moments where he was unsure himself. Namely: his second chance with Clara. It was certainly harder to tell fiction from fact too, given their extraordinary lifestyle. He wondered if Clara had imagined the ice cream pain appearing again - something he frequently fell victim to. Clara stared intently into his eyes, searching for some sort of reassurance. She registered that she'd find none when his eyes finally settled to the floor.

"You too huh?"

"Me too." he simply stated, bringing his eyes back to hers.

"We can talk about it on the TARDIS, if you'd like?" Clara offered. The urge to hug him had crept up on her like a tiger would with its prey. He began his pace again to the lift before she could consider it properly.

"Of course." he replied sincerely. She frantically tried to keep up with his long strides.

They called the elevator and waited with a few other nameless faces. The Doctor, for once, stood still in deep thought. _Well I certainly killed the mood,_ Clara thought sadly. They were the last to enter the lift, but as she went to step inside, his arm shot out to stop her. She backed away from the lift without question. The hospital residents disappeared behind the sliding doors.

"Clara, tell me, what exactly did you see?"

"Well, don't laugh but… I saw a nurse with a cat face. Cat people aren't aliens…" she chuckled dryly, hoping to lighten the mood. Once she saw the gears turning madly through the Doctor's widening eyes, her heart skipped a beat.

"Perhaps you weren't hallucinating after all…"

* * *

 **A/N:**

Hi guys! Thanks a bunch for reading. It's been a long time since I've written something with a lot of dialogue. Reviews would be kindly appreciated. I'll try to update soon as this will be a multi-chapter fic.


	2. Investigation

**_Chapter_** ** _2_**

"Seriously? No, that means that this is a thing. This cannot be a thing!"

"Well it might not be. It might just be that you've imagined it. It really doesn't take a lot of anaesthetic for you humans to see stars." The Doctor explained, observing Clara's sceptical expression. "Oh who am I kidding? It's a thing. It definitely fits the Sisters of Plenitude's profile."

Clara groaned. He had spent the last few minutes quietly briefing her on the Sisters of Plenitude, and their unethical human experimentation on New Earth in the far future. It sent a wave of shivers down his spine to think of such obscenities occurring even earlier in Earth's history. _Questions, questions, questions. All to be answered before we should jump to such… conclusions,_ the Time Lord thought to himself.

"Okay, so first on the agenda: investigate to see if it's one-hundred percent a thing. If it is, then we see if the cat's house trained. I really hope it is, don't want particularly want to drag my cast around…" Clara said hopefully. She leaned casually against the bare corridor walls, firmly grasping her cast when she mentioned it. The Doctor eyed the cast briefly from across the width of the corridor with a frown _. The cast probably won't be much of a problem…_ He blinked in quick succession, before returning his attention to her.

"And if it's not?" he asked with a yawn. It was probably best not to show his interest in the potential 'thing'. _When I last encountered the Catkind species, there was hardly any of them left. I guess New Earth came to us then,_ he supposed. Clara considered what he'd said for a moment, then pushed herself off the freezing wall into a saunter towards him.

"Well, we'll do what we always do. Be there in time to save the day," she stopped before him, craning her head up to get a better look at his face. "And for the record, you really should check to see if you have a curse."

"Maybe you have the curse, seeing as I wasn't present when the 'thing' happened." The Doctor shot, air quoting the word 'thing' for added effect. Clara let out a short, cynical laugh as he sidestepped her to walk back down the corridor - away from the lift.

"Yeah, but we all know that a criminal often comes back to the scene of the crime. Wait, where are you going exactly?" Clara called after him. She broke out into a brisk walk to catch up to him.

"Only arsonists do that. And you'll ruin the surprise if I tell you. C'mon, you'll see…"

XXX

Much to Clara's relief, the Doctor finally came to a stop in front of a locked door, typically branded with an 'authorised personnel only' sign. He glanced around quickly, pulling the sonic out of his breast pocket. Clara rolled her eyes at his lack of subtly. The door gave a satisfying click as the sonic did its work on the lock.

"Should we even be in this part of the fifth floor?" Clara whispered bitterly as he held out a hand - a sign to stay put.

"Probably not. Stay here, I'll be quick." he replied quickly before ducking into the room. A small sigh of relief escaped his lips upon discovering, as he suspected, that this was indeed the right room and was empty. A small couch was angled in the far corner of the room. It was positioned to face the television that was upon a desk along the wall. The closest corner to him had two bunk-beds with lockers between them. On spotting the lockers, he went to open them. _Shoes, no. Scrubs - hmm maybe next time. Ah, here we are._ He pulled out the white coat and tried it on. _Bit short, but it'll do the job,_ he mused inwardly.

Clara grew restless as she counted the seconds that passed. Each second brought them closer to being discovered. She didn't want to get into any unnecessary trouble at her local hospital. Finally, he reappeared in his disguise.

"That's what you were in there for? A disguise?" Clara said with an incredulous tone. He gave her a smug look, buttoning the white coat with care. She'd took notice of the sleeves of the coat being a bit too short for him, and had to prevent herself from smiling to keep her frustrated appearance.

"No, so people have a better chance at guessing my name. Now, if you'd be so kind as to let me get on with the investigation." he extended his arm in the direction that he intended to speed off to.

XXX

"I thought I saw it 'round here somewhere… Ah! There it is." Clara exclaimed gleefully. They'd searched corridor after corridor for a while before coming to a junction of two hallways. The large sign 'Nurse Station' was the first thing their eyes settled on. Underneath the large sign was a wooden receptionist desk. A tired young woman manned the buzzing phones diligently. The pair noticed from behind the counter, there was an ajar door. Significant amounts of chatter seeped through. The lady looked up at the Doctor as he approached, holding up a finger as she finished the call.

"Sorry sir, may I help you?" she asked. He pulled out a black wallet with a blank piece of white paper and flashed it to her.

"I'd like to speak with some of the nurses on this floor. We have questions." he squinted at her to look impatient. The woman's face instantly froze when she saw the card. It was never a dull moment when witnessing a person register what the psychic paper induced them to see. She shuffled and rearranged papers on her desk hurriedly, then stood up to wait for him at the door.

"Her too?" She pointed at Clara. He nodded in affirmation as he and Clara came around the counter. The nurse pushed open the door slowly to reveal the nurse break room. Dozens of people in royal blue scrubs paced about; chatting, eating and resting. The crowd didn't seem phased by the sudden presence of two unfamiliar faces.

"I don't see any cat-people." Clara murmured to the Doctor, who stood awkwardly by her side. He turned his head to address her.

"But maybe someone here has."

XXX

"That was absolutely embarrassing."

"Next stop, the control room."

"Doctor, they thought we were mad!" Clara said in an exasperated undertone. The two nodded, in thanks and in farewell, to the lady at the counter when they had exited the nurse break room. He waited until they were out of earshot down the corridor before replying to his companion.

"Don't be ridiculous. We had a good cover story - and I had an exceptional disguise." he patted his white coat, looking pleased with himself. Even though he was an alien - and being used to a variety of looks his way - he couldn't help but feel a tiny bit threatened by Clara's judgemental stare.

"Thank God we didn't go for facial mutation…"

"Pfft. I thought it was better than 'trying to find the culprit of a cat-mask prank'. Anyway, we need to get to the control room on this floor to see the surveillance tapes." The Doctor explained as he led the way once again. _This better not become a wild goose chase,_ he thought fretfully.

The trip to the control room was surprisingly quick. He insisted to Clara that it was good observation and memory - but he knew otherwise. They entered the small room, which was lined with rows and rows of small television screens. Amazingly, it was all for the fifth floor only. The Doctor did his usual psychic paper stint with explanation to the gruff surveillance officer, and Clara soon found herself watching, well, herself.

"Good times." Clara joked as the footage of two nurses wheeling her gurney across the room came on screen. The Doctor let out a small chuckle as he pressed fast-forward on the tape player. Twenty minutes-worth of nothing flew past their eyes in a couple minutes before Clara let out a small gasp.

"Stop! There," she pointed to the screen. "That was her. It must've been." she scrambled to pause the video. The Doctor peered at the now still image of a nurse beside Clara's gurney. However, from the angle the camera was positioned, it was the back of nurse's head that they were treated to.

"Of course! The camera had to be facing the wrong way." The Doctor spat as he resumed the video. They watched with disbelief as the nurse rounded Clara's gurney - without revealing her face to the camera - and disappeared through the double doors. Clara scanned the nearby television screens for a possible second camera-angle, but to her dismay, found none. Exhaling deeply, the Doctor restored the screen to its current live footage. Clara looked away from the screens to him, pursing her lips. He stood there for a few seconds, leaning with both hands firmly clutched to the messy table in front of him. He was contemplating their next move. The security guard broke the silence.

"No luck huh? Don't worry, sir. If the suspect does show her face I'll let you know." the elderly security officer reassured, tapping a nearby screen to fix the static on the image. They both thanked him and loitered outside to gather their thoughts. The man inside the surveillance room could be heard grumbling something about 'silly prankers'.

"Look, maybe it's not a thing. If she exists, someone would've definitely saw her wandering about and spoken up about it, even if she had a surgical mask on. She would have also done _something_ noticeably bad by now if she's not friendly." Clara surmised. She looked around for a clock, and spotted one hanging above a doorway close by. It read half past seven, to Clara's surprise. The Doctor scratched the back of his head, considering her words carefully. _Perhaps we should let it go - and get her head checked out._ He caught her expectant stare and straightened up quickly.

"Hmm, I suppose so. Okay, back to the TARDIS then. We'll be back soon anyway. So if we get any other rousing suspicions…"

"When we come back, I'll be checking out as soon as possible." she scanned his coat, realising he was probably becoming a bit attached to it. "By the way, you really should return the coat before we-"

An audible yelp from inside the control room startled Clara. The two of them burst through the door to see the security guard, with a dropped jaw, unable to tear his widening eyes away from one particular screen. When they ventured further inside the enclosed space, they noticed that he was looking at the exact same television that they'd investigated previously. The image on screen was live - broadcasting the same recovery wing that they'd seen earlier - but with a dozen or so nurses scurrying about. Their actions were clearly panic driven as they hurriedly wheeled gurney after gurney away from one isolated patient. The Doctor and Clara watched in horror as that isolated person convulsed. Their face was contorted with agony. Clara felt her arm being tugged, pulling her away from the haunting sight.

"Evacuation in a recovery ward isn't a normal response to a patient having spasms. Come on, we've got to get down there!"

* * *

 **A/N:**

Hi all. Thanks so much to those who've reviewed, added this story to alerts, or favourited. It means the world! I've spent the past couple of weeks mapping this story out in great detail, so expect 8 chapters from me (at least, I may add more to the story if I feel that's what needs to happen). Any pointers or advice about anything are very much welcomed! Thanks again. :)

 _P.S: Enjoy the banter while you still can…_


	3. Revelation

_**Chapter 3**_

Yellow tape, bearing the word 'caution', was strung across the hallway neatly - almost as if it were webbing designed to catch vulnerable prey. Beyond the tape, The Doctor and Clara could see people in yellow hazmat suits wander around the corridor leading to the recovery ward. _If they were going for subtle and quiet, they certainly hit the nail on the head,_ Clara thought sarcastically.

Clara swallowed hard, taking in what could have been a scene straight out of a horror film. "Doctor, I could - I was in there… Only - only a couple hours ago…" panic began to constrain her voice. He grabbed her good arm gently, hoping to calm her down. With his free hand, he held up a finger briefly, then pulled out the sonic screwdriver and rolled it on the palm of his hand.

"I'll do a diagnosis - even though, I believe, if you were to have been infected with something, it would've shown by now…" he consoled. Clara held her breath as he scanned her head and body. Other than the beep it made when it hovered over her cast, the device remained undisturbed. The Timelord flashed a quick grin at Clara and gave her a slight squeeze. "Nothing to report."

"Oh, thank God." she managed, resuming her breathing. The Doctor noticed that they were slightly quicker breaths than previously, but that was understandable. He released his grip on her, momentarily distracted by the flickering lights above them. Shaking his head in distaste at the obsolete lighting, he peered through the tape, looking to grab someone's attention.

"Oi, you! I need to talk to you for a minute." he called to a passing hazmat operator. The yellow cladded figure stopped in his tracks and turned his head sightly, considering whether to engage the Scottish man that was pointing at him. A gas mask covered his face, preventing the Doctor from seeing his condescending expression. It was clear that he wanted to dismiss the pair as quickly as possible. The masked man's tone of voice was what tipped the pair off about these intentions.

"Sorry Doctor, no access. This area has been cordoned off from the general public." he waved almost mockingly and spun on his heel to leave them.

"You haven't even checked our credentials." The Doctor spoke with an air of authority. Raising the psychic paper, he shoved it through the tape and into the man's face as he came back to check.

"Oh… apologies. Um, I didn't realise you lot would be here so soon. Please - uh - come through." he stuttered. The man raced to pull the tape up so the two could lean under. "Sorry, name's Parker. You'll need a hazmat suit. The immediate door to your left is where the temporary decontamination station is - they'll issue you with one in there."

"Appreciate it." The Doctor responded coolly. They made their way to the station in silence. Surprisingly, the corridor was also quiet, with the exception of the air ducts clunking and wheezing noisily. A medical officer, dressed identical to Parker but with the exception of a black armband, was occupied with cleaning the hazmat suit of a fellow colleague. The person stood in what looked like a small grey inflatable pool. The medical officer finished scrubbing the yellow suit and had wheeled in a portable hose to do a final wash.

"Ma'am, we've got government representatives here. Probably want an update on the situation." Parker addressed the officer. Without waiting for a reply, he promptly left the room, leaving the two to wonder who was controlling the operation at hand.

"Back again eh? I thought we made ourselves clear when we agreed on keeping all this tight-lipped. What could you lot possibly be back for?" the medical officer asked irritably. She'd finished hosing down the hazmat operator and walked over to Clara and The Doctor.

"Not to worry, the deal is still being upheld. We're just here to inspect the body. I've been brought in since I specialise in this sort of thing."

"Hmph. If our organisation can't identify the reason for these… happenings, then I don't see why they'd send you here - but alright. Doctor…?" the woman huffed in disbelief, extending her hand.

The Doctor reached out to take her hand. "The Doctor will do. This is Miss Oswald."

"Pleasure to meet you both. My name's Officer Jenkins - chief medical officer, that is," she then proceeded to shake Clara's hand, "I'm in charge, for the most part, of quarantine control and decontamination. You'll be issued with type 1 hazmat suits - only because we haven't a clue as to how the virus spreads."

"You think it's a virus?" The Doctor mused. He rubbed his hands together in anticipation, eyeing the chemical-resistant gloves and boots that were neatly placed at the far end of the room. Officer Jenkins regarded the pair for a moment. She was tempted to inquire more about the strange old man's 'specialisation', as she assumed that the government would have provided him with details of the situation.

"Well, yes. Seeing as the 'host' is the antibody. We've never seen anything like it - it just shuts down the antibody completely."

Clara's eyebrows knitted together. Although she was aware that she didn't specialise in biology, she knew that viruses didn't behave that way. That caused her to steal a glance at the Doctor. His expression was clear: he was equally as dumbfounded as her. _Surely not for the same reasons,_ Clara hoped. She decided to choose her next words carefully to keep up their risky façade.

"Cells act as hosts though. The last time I checked, the antibody wasn't a cell?" she purposely wondered aloud. The Doctor nodded thoughtfully. He racked his brain trying to pinpoint when in time such a virus existed. It was definitely alien in origin - that was for sure and certain. He also speculated that because of its unknown origins, that was the reason for it being swept under the rug by this… unknown agency.

Officer Jenkins unzipped a large black bag and produced a yellow hazmat suit. She approached the Doctor with it. "Right, suit up then. Go see for yourself."

"No suit for me then?" Clara raised an eyebrow at the chief medical officer, placing an arm on her hip as she did. _The Doctor has dragged me along on this joy ride - and now that something has finally reared its ugly head - I'm not going to be sidelined._

"Uh, well, since you have a broken arm, I just thought that - "

"I'm his supervisor. I need to be present during inspection of the body. I'll only be observing and evaluating. Promise!" Clara cut in with a wink. She collected the yellow overalls, black boots and gloves, and went to change. Minutes later, Clara and The Doctor regrouped, fully dressed in the protective gear. Clara put the gas mask on and tightened the straps. From the corner of her eye, she could see the Doctor quickly inspect her gas mask to see if it was fastened securely. He was exceptional at concealing various things, but his concern broke through that mask sometimes. She pulled the hood over her head and took in a deep breath.

"Well the air's certainly better in here!" she quipped. They speedily went through safety checks of the equipment, then left Officer Jenkins at the station.

Inside the recovery wing was chaos. Everywhere the Doctor looked, there was someone busy decontaminating something or scribbling down information hastily. His gaze turned to the security camera that sat in the corner of the room. The tiny red light that would have usually been present was absent. Finally, his eyes settled on the only gurney in the room. Clara spotted it too. It suddenly hit her that the patient wasn't thrashing about anymore. Rigor mortis had set in…

"So, erm, are you sure that nothing _alien_ can get through these suits? Because I know - that you know - that this virus thing isn't from Earth. So…" Clara asked, clearing her throat. He had to tear his eyes away from the chilling scene to refocus on the question.

"Fully sealed systems at overpressure to prevent contamination - even if the suit is damaged. Nothing's getting through this gear, Clara." he informed her. Without another word, they slowly crept up to the gurney. At present, there was only one person hovering over the pale body. The examiner was in the middle of inspecting the glazed-over eye. It was blood red.

Stooping down for a closer look at the eye, The Doctor spotted no pupil or iris fibre structure. It was as if he was staring at a perfect crimson circle on a palette. A thin black outline prevented red from seeping into white. "I always find it so fascinating how quick you people scramble to cover up things like this."

"Ah, you must be the Doctor, it's a pleasure to meet you. I'm Doctor Robinson. I don't suppose you'd know anything about this virus, would you?" Dr Robinson addressed them in a raspy voice. Ignoring the Doctor's previous statement, he continued to flash a tiny light into the eye, not looking up to formally greet the new guests.

The Doctor chuckled lightly, finishing up his examination of the eye. He raised his head to try search for Dr Robinson's eyes from behind the gas mask's tinted glass circles. "Ah, straight down to business then. I can already tell that we'll get on famously. Tell me about the eyes."

"They weren't always like this - during the virus's attack, a nurse reported seeing the pupil slowly fade. The iris discoloured - transforming into the red we see now. The sclera was also populated with green veins… before disappearing completely upon death."

"Were there green veins anywhere else?"

"Yes, the body's veins protruded in the same fashion as the veins in the sclera - until it, too, disappeared -"

"So it left the system then?"

"It would appear so-"

"And that's why you haven't a clue what the virus is made up of? It doesn't stick around long enough to be properly examined. Hmm," The Doctor quickly transitioned from conversing with Dr Robinson to himself. The human watched the Doctor's sonic with intrigue as it scanned the body.

"Question: What substance leaves the body quickly without a trace?"

Clara watched with a small grin as the Doctor pace around the gurney, prodding and fiddling with the screwdriver. It was certainly enjoyable at times to see him in his element.

"Conjecture: Viruses don't leave the body easily - they leave it in one of two ways: Using some form of remedy, or, until the host dies. However, it seems as if the patient died far too quickly - inhibiting the production of antibodies. Usually, a virus wouldn't kill off its 'host' quickly, so as to prolong their lifespan. It would only be fair to assume that something else is at play while the virus attacks the immune system - it's allowed access while the body's defences are down."

"So it's a virus and a poison then?"

"Mmmh, an advanced toxin perhaps." The Doctor said, half to himself. Clara stood there for a minute, mulling over the flood of information that she'd gathered over the past hour.

"Are you absolutely sure it's contagious? What if - if the patient was being forcefully exposed to this toxin, uh, in some way?" Clara asked quietly to Dr Robinson. The Doctor turned on his heel. He, too, waited for an answer.

"Well, we're not one hundred per-cent sure. We've studied each of the bodies and haven't come across any unauthorised invasive procedures - besides, of course, the operations they've had whilst being in the hospital."

"Bodies? There - are there others like this?" Clara stuttered, partially in disbelief and mostly in fear. Dr Robinson nodded indifferently. He gathered his equipment and motioned for the pair to come with him.

"I can take you to the others, if you want? Otherwise, It's the end of my shift, fortunately." he offered, almost impatiently. The Doctor and Clara looked at each other for a moment. Finally, the Doctor shrugged in a 'why not?' sort of fashion. The white sheet was replaced over the body, and the group exited the recovery ward.

XXX

After being cleaned at the decontamination station, Clara and the Doctor went to take off their suits - but Dr Robinson waved his hand nonchalantly at them.

"Oh, don't bother taking the hazmat suits off. We'll only have to put them back on when we enter the morgue." Dr Robinson explained. He headed for the door when the Doctor stopped him in his tracks.

"What about being covert?"

"The lifts are particularly close to here, I'm sure we won't raise much attention in that short amount of exposure to the public." he replied, brushing past the Doctor and entering the corridor.

Clara patted the Doctor on the shoulder with a laugh. "Since when are you worried about being covert? We're never covert!"

The group of three passed under the yellow tape and hurried down the almost abandoned corridor of the fifth floor to the lift. The handful of people they saw seemed to wander aimlessly - almost as if they were in their own world fighting fatigue. Others broke into fits of coughing. _Well that's odd. I suppose we are in a hospital…_ Clara thought as they sped past.

Once inside the lift, Dr Robinson clicked the basement floor button and scanned his ID card for confirmation. The elevator whirred to life and slowly made its descent down. Inside the compartment, it was unusually silent. Clara shifted uncomfortably in the suit, checking to see what the Doctor was doing. He had a hand against one of the walls, pondering quietly. She then turned her attention to Dr Robinson, who stood motionless in front of the compartment doors. As soon as the doors opened, he was the first to exit into the basement.

Clara had found, once again, questioning whether she was in some sort of horror film. The crummy brick corridor - lined with ancient copper piping along the ceiling - was very eerie. The lights were not as bright as the ones upstairs. Above ground had also teemed with life. Here, not a soul was in sight. Dr Robinson barged on, leaving the two of them in the dust. _He's probably just as keen to get out of here as I am,_ Clara supposed. The rattle of what sounded like malfunctioning machinery echoed throughout the corridor, concealing the Doctor and Clara's hurried footsteps. The Doctor recognised the familiar wheeze of the ventilation shafts - and how it had multiplied considerably.

"The morgue is just around this corner. We cordoned off a section specifically for these bodies." they could hear Dr Robinson's gravelly voice just barely from over the noises. They walked on, coming across a door that was ajar. Clara peeped inside as they passed by, briefly witnessing flashes of light. Whatever was behind this door, it also seemed to be the source of the racket. The lights began to flicker on and off as they rounded the corner and entered the morgue.

"Something wrong with the generator here, doctor?" The Doctor asked when they closed the morgue door, barely muting the noise outside. Dr Robinson nodded at a morgue attendant, who was also in a hazmat suit. The attendant left them swiftly, and the Doctor questioned him again - this time with a harsher and impatient tone.

"Is there something wrong with the generator?"

"How would I know? I'm a doctor, not a maintenance man. All I know is that the power has always been faulty." Dr Robinson snapped. Clara raised her eyebrows at the sudden hostility. Figuring he was probably looking to leave, Clara decided to ease the tension.

"Sorry, uh, one last question - then I think we can take care of ourselves down here. You can go, in other words. Sound good?" she reasoned, glancing quickly at the Doctor to see if he didn't have any other questions. He didn't object, and Dr Robinson nodded with a smile.

Clara continued, staring at the door to the secluded area where the rest of the infected were. "Right, so why keep the bodies down here then? I'm sure you'd have much better facilities wherever your organisation's headquarters are."

"As your friend here was worried about before, it's all about covert operations. We'd have the media on high alert if we wheeled out five bodies in five individual quarantine chambers out the front door."

"Fair enough. Thank you for your time Dr Robinson, we can take it from here." Clara gave a polite grin as he shook hands with the two of them. Dr Robinson made his way towards the door, and was greeted by the morgue attendant. The Doctor watched as the morgue attendant quietly relayed information to Robinson. They both disappeared out the door without sparing the pair another glance.

"Charming fellow." The Doctor muttered half-heartedly. He was clearly wrong about the man, Robinson wasn't someone that he'd befriend in a hurry. Clara picked up on these thoughts quickly.

"Yeah, bit of a temper on him. I suppose he wasn't being paid for overtime…" Clara joked.

The Doctor approached the door, peering through the circular glass window. Inside was what looked like a small laboratory. At the far end of the room, four gurneys lined the back wall. Each had a white sheet pulled over. He took a deep breath, then pulled the door open and stepped inside.

XXX

Clara watched the big hand on the clock pass the six and yawned involuntarily. It was half past nine now, and she was already set on sleep. The Doctor had examined each individual thoroughly, while she had flicked through their records, looking for any similarities between victims. _This is certainly not what all those crime dramas make it out to be,_ Clara sighed. They worked quietly, only making a comment or so to each other if something vaguely interesting popped up.

Clara groaned and put the papers down, directing her attention to him. She needed a break, and conversation was sorely needed. "You really are worried about this, aren't you? You've been engrossed in this since I mentioned seeing that cat-lady."

The Doctor gently placed the still woman's hand back onto the gurney and swivelled on his chair to face her.

"I know the information I gave you about The Sisters of Plenitude wasn't enough to see the full picture, but these… _monsters_ are not to be taken lightly. If they are behind this, then we need to act fast before they make the next move. If we -" the Doctor trailed off as the lights went out. It was pitch black inside the room. The Doctor could hear Clara sigh, followed by a light thunk against something wooden. He pulled out the sonic and illuminated the room. Sure enough, he could see that she was still seated across the room, resting her head on the desk.

"C'mon, there's no time for a snooze. We've got a generator to fix. It's a good thing I'm both a Doctor _and_ a maintenance man." The Doctor poked, trying to make light of the situation. He could hear Clara mutter something about 'not a competition' under her breath. She finally stood up and went over to him. They both knew it was out of the ordinary for a generator in a hospital to go out. What was unsettling to them, however, was that the backup generator had not immediately kicked in. They raced outside into the morgue area when the backup generator showed no sign of coming online.

"Can we take off these hazmat suits now? It's really starting to get tiring just walking in this thing." Clara asked him. From what he'd gathered while inspecting the bodies, there was no trace of the toxin. He was almost certain that Clara was correct - they'd been infected purposefully somehow, and were not contagious.

"Yes, it should be safe to do so now."

They peeled off the hazmat suits and gas masks. Clara heaved a sigh of relief as she regained maximum mobility of her limbs - excluding her right arm. She watched the Doctor toss the laboratory coat onto the floor and button his black coat up hastily.

Stepping out into the corridor, Clara trembled. She didn't realise how cold it was outside of the hazmat suit. The Doctor looked up and down the corridor, clearly unfazed by the change in temperature, and gave a small huff.

"Doctor, I think I saw the generator room back this way. We need to hurry, there are patients who probably need the power back on as soon as possible!" Clara exclaimed and took off down the hall. They skidded to a halt in front of the ajar door, unsure of whether it was the correct room.

"Sure would be good if they labelled these doors properly." she said between short breaths. Suddenly, the unmistakable glow of a flashlight could be seen through the crack in the door. The Doctor slowly opened the door, holding out the sonic in front of him. The creaking of the hinges caused the flashlight to disappear quickly. Luckily, they made out the shadow of a person just before the light source was switched off.

"Show yourself!" The Doctor commanded gruffly. They hovered at the doorway for a moment, before a faint buzzing sound enveloped the basement. The overhead lights had sprung back to life - although just barely. The room and corridor behind them were lit even more dimly than before. The bulbs also began to quiver frequently.

Clara stood still beside the doorframe while the Doctor ventured inside. She took in her surroundings, noticing a copious amount of gas canisters lying about the empty room. "About time the backup generator kicked in." she heard the Doctor whisper to himself, before disappearing through another open doorway into a hidden room. Clara paced over to the new room, only to bump into the Doctor. He stood frozen a metre from the entrance, glaring at the large machinery that took up most of the floor space.

"I was wondering when you'd show up." a sinister voice mocked from behind the machinery. The Doctor put an arm out in front of Clara, then addressed the unseen person.

"Ah, the long awaited revelation at last. It's good to finally meet you, uh…?"

"Sister Xeka," the hidden figure replied. She moved around the machinery to reveal herself. Her cat-like facial features and grey fur were now highlighted under the dim basement spotlight. Clara watched in awe as Sister Xeka's slitted pupils dilated when exposed to the sudden brightness. Her emerald green eyes - almost iridescent in nature - darted from the companion to The Doctor and narrowed slightly.

"You haven't a clue how long I've been looking forward to this meeting… Doctor."

* * *

 **A/N:**

Boring stuff is now over! The next couple of chapters will be intense, I promise! I didn't do biology in my senior years of high school, so sorry if the info is a little messy or incorrect!

Please leave a review if you enjoyed this! It would mean the world! Thanks for reading. :)


	4. Damnation

**_Chapter 4_**

"Good to hear you lot haven't forgotten about me. You'd think that would've scared you off by now…" The Doctor growled between his teeth. Sister Xeka, who still kept her distance, merely snorted.

"Quite the contrary, actually." she sneered. Her eyes fell back onto Clara, who was still taking in the humanoid's appearance. Apart from her face, she looked human in her bloodied scrubs and unworn surgical mask. _That's probably how she's kept hidden for so long_ , Clara realised.

"You know, he used to like them blonde. I suppose that was a long time -"

"You need to stop meddling with the generator. There are people here whose lives depend on it! Turn that off _now_ , or you'll regret it." Clara interrupted angrily. She pointed towards the large contraption that was connected to the dead generator with large cables. The device, which had a canister of gas connected to its side, sported a large tube on top. The long industrial tube trailed upwards and into a ventilation shaft near the ceiling. It hummed loudly, occasionally vibrating here and there. The Doctor peered at the unlabelled gas canister, dread slowly filling him.

Sister Xeka followed the Doctor's line of sight to canister, and smiled deviously. "XLR8-Alpha Toxin. It's the unofficial predecessor of the rare Speciformer drug. Being stuck in this day and age hasn't really helped advancements, unfortunately."

The Doctor clenched the screwdriver tightly, scowling at the Cat. "And you're pumping it into ventilation shafts? Oh, we can't have that." He aimed the glowing green tip at the contraption. Sparks erupted from the machine, causing the tube to stop rattling abruptly. Satisfied with his handiwork, he turned his attention back to the unmoving Sister Xeka. What surprised him was that she still held her knowing grin, and didn't move to stop him from damaging the circuits of the device.

"It's really too late for that, Doctor. It's been running for almost two hours now on the main generator - it started to drain the backup one." She rubbed her hands together excitedly, taking a couple steps towards the two. "If you arrived a couple weeks ago and did that - you would've stopped me from mass producing the toxin with the generator. But, this is now a fixed point in your timeline, so you lost that battle."

He flinched at the mention of the workings of time travel. Questions flooded his mind, but one was already formulating on his lips.

"Who brought you here?"

Sister Xeka ignored him. Instead, she waltzed over to Clara. "I'm curious to see results, as I haven't tested the toxin in its diluted gaseous form. The concentrated liquid dosage was too powerful - as you've witnessed. Only one man has fully embraced the concentrated toxin."

As if on cue, the pair heard heavy footsteps behind them. Clara turned her head slightly to see familiar yellow overalls in her peripheral vision. Dr Robinson stood tall, blocking the door - their only exit.

"The mortality rate was far too high, so we altered it to a gaseous form. It's slowly, but readily, absorbed into the bloodstream now - successfully initiating the transformation." Dr Robinson finished her explanation. The Doctor and Clara backed away slightly from the man as he lowered his yellow hood, freeing a mop of sweaty black hair. He began to remove his gas mask, allowing his piercing crimson eyes - ablaze with anger - to drill into the two who stood before him. Green veins, which stuck out unnaturally on his neck, twitched as he spoke again.

"I hear them. Their voices. They've awakened…"

The puzzled look on their faces only delighted the Sister even more.

"Hive mind," Sister Xeka answered their unspoken question. "As much as I wanted to saturate the toxin with feline DNA, I needed to insert strands of other species to fill the gaps. Collective consciousness chose to break out... How fascinating."

Clara noticed her friend's increasingly aghast look. It made her wish that they'd left for the TARDIS instead of pursuing this nightmare.

"So you wanted Santa to come early - bioengineer something similar to your species earlier in human race history," His lips curled slightly as he spoke his next words with venom. "You don't belong here, Sister."

"You don't either. You belong in a graveyard, old man - long and forgotten. You deserve retribution for the shame you've brought on my people. And as the Goddess Santori would have it, my quest has brought you to me to fulfil that destiny." she shot, snapping her fingers bitterly. Dr Robinson lurched from behind them. He lunged at The Doctor with surprising force, sending him flying into the generator.

"Robinson, contact the Changelings. Tell them to come downstairs so they can partake in the reckoning…"

Clara raced over to the winded Doctor as Robinson froze, closing his eyes to communicate with the Hive.

"Time to run!" Clara tugged at his jacket as he clutched his abdomen, collecting himself after the harsh blow. She pulled him up and they blundered to the exit. Robinson redrew his focus to his surroundings. Sister Xeka chuckled lightly, beckoning for him to give chase.

They sprinted aimlessly down the darkened corridors, formulating some sort of plan between themselves.

"We need to head to the roof. I don't know what the situation is throughout the hospital - or if the toxin has dissipated, but we need to examine the gas from inside the TARDIS." The Doctor explained as they came to a stop at a t-intersection.

"I don't remember seeing this. That means the elevator was back the way we came! Maybe we can find a stairwell." she suggested, frantically searching up and down the new narrow passageway. Reluctantly, they picked the left hallway when they heard the echo of more than one pair of feet. The two barrelled forward, aware that their pursuer now had friends. The amalgamation of noise from behind them got louder and louder. Robinson and the Changelings were gaining on them due to their enhanced physique. The pair jumped up a very small flight of stairs, leading to a sublevel of an open area.

Clara spotted the stairwell picture above one of the heavy doors in the large room they had entered. "There! C'mon."

The Doctor pushed on the door, entering the concrete stairwell. He held the entrance open as Clara ran through. Spotting Robinson and two other beings in hazmat overalls leap up to the sublevel, he violently slammed the door and soniced it to lock it.

"Up. Now!" He yelled. They took the steps two at a time. Each pound of the locked basement door kept their tired legs from giving way. When they reached the first floor, the sound of metal finally breaking rung all through the stairwell. Clara peeked over the railing on the first floor landing to see the men begin climbing the stairs. She was about to relay this information to the Doctor when suddenly the first floor door was torn open beside her.

"Clara! Keep moving!" The Doctor called from halfway up the second floor stairs. She continued in his wake, narrowly avoiding two changelings that had stumbled in from the first floor. By the time they had reached the third floor, her legs were on fire. She could feel her cast grow heavier by the second. _They're gaining on us even though we're flights ahead. We're not going to make it to the eighth floor at this rate, we're -_ her thoughts were interrupted when The Doctor stopped dead in his tracks. They had passed the third floor landing and were attempting to climb the flight of stairs to the fourth. His gaze was trained upwards. She followed his gaze, and sure enough, saw pale hands grasping onto the railing above them.

"Exit, stage left!" he rasped through his burning throat. They backtracked hastily down the stairs to the third floor landing and exited into the darkened hospital corridor.

"We can give the lift another go, yeah?" Clara asked him. They surveyed the empty hallway briefly, before resuming their escape from their relentless hunters. The door behind them flew open, revealing Sister Xeka to be amongst the pack of mutated humans.

"Don't let them get to the TARDIS!" the Cat bellowed. The Changelings swarmed around her and pelted forward towards their prey. She held out an arm in front of Robinson before he passed her, making him keep pace.

"Head upstairs…" Clara could hear the Sister's calculative voice getting softer and softer. She risked tripping to look back at their pursuers. Sister Xeka came to a stop, finishing her command to Dr Robinson. The man nodded and took off in the other direction. Two other hospital patrons, both with a sluggish walk and green veins protruding, joined him. Clara refocused on the Doctor, who was attempting to control his breathing.

"How is she controlling them?" he huffed beside her. She shook her head in utter shock. Her heart felt as if it would beat out of her chest. This time they both looked back. The handful of changelings that were chasing them had multiplied exponentially. The lights above frequently gave way, concealing what was ahead…

"You cannot escape your damnation, Doctor!" Sister Xeka called from behind the vicious pack. A flurry of footsteps echoed through the corridor as The Doctor and Clara charged on as fast as they could. Almost every doorway they passed had some sort of Changeling burst out to join the chase. Some of them had the jump on the pair, coming out of hidden crevices just ahead of them. Seeing this, the Doctor pulled ahead, taking Clara's left hand in his right. He managed to bulldoze through the first couple easily, but as more and more poured out in front of them, they found themselves scratched and clawed at. The Doctor could feel his joints on the verge of breaking. The creatures had torn through bits of his jacket, leaving scolding cuts and scratches all over his arms, lower stomach and shoulders. _Just a little bit further…_ Clara pleaded, sparing a split second glance at the Doctor's injuries. She too looked like a dishevelled mess as she fended off the rabid beings. A few clobberings with her cast had caused a split in the material. The broken pieces slid off Clara's arm, leaving her defenceless. From behind the gathering mass of Changelings in front of them, they spotted the large metallic doors of the lift. It half opened and closed in quick spasms. The insides were shrouded in shadows.

"I can see it!" Clara exclaimed as she leapt over an unmoving man. The crowd thinned towards the end of the corridor, giving the Doctor a window of opportunity to kick-start the malfunctioning lift before the Changelings caught them. The Doctor readied his screwdriver as he got near. He pointed it towards the lift, causing the jittering doors to remain slightly open - enough room for them to individually slip through. Clara squeezed his hand tightly. They narrowly dodged a swipe from a changed nurse, causing them to lose a bit of speed as they came within metres of the doors. The Doctor slid through the small opening first. A strong tug at his hand prevented him from moving further into the safety of the dark compartment. His heart dropped to his stomach as he heard a cry of pain directly behind him. He swung around quickly to see Clara - whose face was stricken with agony - stuck halfway through the opening. With one hand still intertwined with hers, he tried desperately to pull her through. The other hand still had the sonic operating, preventing the doors from squashing her.

"They've grab-grabbed m-my arm." She wheezed. More hands grasped every part of her body. The Doctor's grip on Clara began to slip, but he continued the almost impossible tug of war - thriving off the adrenaline that kept his muscles from shutting down. Their eyes locked; his radiated determination, hers was full of terror. They broke eye contact, however, when the lift jolted violently. It swung back and forth, crashing into the sides of the elevator shaft. Gravity had wrenched him away from Clara. He crashed back-first into the rear of the compartment, dropping the sonic. It cluttered below on the floor. The lift was now oriented diagonally - the highest point being where the doors were. One of the two cables had been severed, leaving the lift to dangle dangerously above a deadly drop. Clara, now being dragged backwards into the pack of Changelings, screamed and thrashed about. She took one final look into the lift as the doors slowly slid shut. The beaten Timelord lay crumpled at the bottom of the compartment. He snapped his eyes open in time to see her disappear.

"CLARA!"

"DOCTOR!" she cried, watching helplessly as the elevator doors slammed shut. Clara was then forced to her knees as Sister Xeka emerged from the crowd. A man in a hazmat suit was next to her, whispering. The cat lady smiled, looking directly at Clara with a smirk.

"Tell Robinson to cut the other cable. We can make do with his companion…"

The yellow cladded figure nodded, lowering his head to relay the information through the Hive. The elevator shaft immediately rattled. The unmistakable, heart-wrenching sound of metal scrapping on metal that emanated from behind the closed doors was deafening. The elevator had fallen.

"No… What have you done?!" Clara screeched, once again struggling against her captors' hold. Tears flowed freely down her cheeks. _He didn't… He can't…_ Sister Xeka made an audible sigh as she towered over Clara.

She bent down low enough to whisper into the trembling human's ear.

"I don't think he's coming back from that one."

Before Clara could retort, the Sister had brought up her left arm, which sported a small aerosol canister fashioned onto a gauntlet. She flicked her wrist, activating the device. A jet of gas spurt out at Clara. She gagged and choked back more tears as she involuntarily inhaled the familiar cold, sweet gas. _Anaesthetic? Not again…_ Clara thought. The room spun. Her eyelids grew heavy. She drifted into darkness before she felt herself hit the hospital floor.


	5. Dehumanisation

**_Chapter 5_**

The first thing she felt was the chilling wisps of air that bit at her exposed arms. It was uninviting, returning to the conscious world, but she had to force her eyes open - _just for a second_ \- to see where she was. Her surroundings were blurred and hazy. Clara craned her stiff neck down to see that she was sitting on a hospital IV chair, and was bound to it by worn leather straps. She tried to move her left hand, but was rewarded with the material digging deeper into her flesh. _Where's my sweater gone?_ A faint beeping sound hummed behind her in frequent intervals, piercing through her skull like an alarm clock would in the morning. Before Clara could gather any more information, she heard the creak of a door being opened. Shutting her eyes quickly, she pretended to be limp to buy more time. Only one distinct set of footsteps entered the room. The beeping sound that rung in her ears grew slightly more frantic.

"For someone who's still unconscious, a heart rate of 120 BPM is quiet the feat. Open your eyes, Clara Oswald. Don't insult me."

Clara felt her stomach do flips. Begrudgingly, she opened her eyes to meet those of her captor. Sister Xeka sat directly in front of her in a swivel chair. The Cat's emerald eyes never left her prey's brown ones as she fiddled with a controller. Clara quickly averted the humanoid's slits to study her predicament more carefully. A thin wire trailed over her right arm and underneath her white singlet. It presumably stopped at her chest for the heartbeat monitor. She twisted her head to see the screen behind her. The number slowly increased with each passing second. Her eyes then travelled around to study the room she was in. There were plastic coverings concealing hidden objects, and parts of the walls around them were made of timber panels. The walls that weren't of wood, were run down with exposed cables jutting out of holes. _I'm on the seventh floor,_ Clara realised.

"I'd like to draw your attention to the device you're hooked up to," Sister Xeka said, standing up to trace the machinery next to the chair with her finger. "It's basically a miniature version of the machine I was using for the ventilation shaft."

Clara followed the rubber tube from the machine up to where it bent in a 'j' shape. She was directly under the opening.

"So you're going to turn me into one of them? Why? You… You've… you've already killed him. I don't - unless…?" Clara struggled to string together the sentence after mentioning the Doctor. _He must've escaped. Is that why she took me?_

"It was better this way. With him gone, I avenge my race. Also, there'll be less tricks, less funny business and whatnot to deal with in the process of going back home. Now, I consider myself to be well informed. You, my dear, know how to pilot that TARDIS of his. You're going to tell me how to fly it so I can return back to my own time."

The Sister was given a look of utter disbelief. _I have to keep her talking, if there's a chance the Doctor is still alive, then he'll come for me. He always does._

"You could've asked him to take you back! There was no need for this - for any of this - at all!" Clara felt her voice rise uncontrollably. Gone was the fear of what the alien would do to her. The fact that all of this was just for petty revenge and for a ticket home started a fire within her.

"It's not that simple. He ruined us."

"It never is with you lot! Oh, I saw ruin. I saw _bodies_ lying about when we ran. Both bloody and unscathed! People who've died both directly and indirectly from this - this unnecessary -"

"Enough!" Sister Xeka growled. She slammed her fist on a nearby dressing trolley, before pointing the remote at the device next to Clara. "I know you're stalling! No more chit-chat. Are you going to cooperate or not? Either way, this ends with you helping me. It's just that you get to keep your sanity and humanity if you do cooperate."

Clara eyed the device with pure disgust _. I guess that's all the time I could salvage. Doctor, please. Please, if you are alive… Hurry._

"Do what you want, I'm not helping you willingly."

The Cat smiled devilishly. She stood up and made her way towards the door. At the doorway, she spun around to address Clara one last time.

"I'm going to unmake you, Clara Oswald. You get to see it first-hand too." she spat and clicked the button. Clara immediately held her breath as the machine jolted to life. From above, colourless gas hissed out of the tube. Sister Xeka cackled at her slightly inflated cheeks and tightly clenched lips.

"How long can you hold your breath for?"

The door was wrenched shut, and Clara was left alone in the room with the eerie, artificial drone of her heartbeat. As soon as she saw the door close, Clara rocked and struggled against her restraints. To her dismay, she discovered that the chair had been bolted to the floor, preventing it from being tipped over. The leather belts also showed no sign of breaking. Frantically scanning anywhere and everywhere for something, the nagging want of air began.

 _He's not coming. He's dead. No, he's got to be alive. Keep holding your breath. Clara, just take a breath - it's over. He's coming. Just a little bit longer, I'll be fine. I'm not fine._

A minute or so had passed - Clara couldn't tell exactly. She felt her throat tighten. Her head pounded rapidly while her chest felt as if it was being crushed from the inside-out. A fresh tear rolled down her cheek.

 _I'm sorry…_

Clara gasped loudly, taking in a deep breath…

XXX

He held his breath, clutching the service ladder for dear life. Smoke and darkness provided him with cover to hide from his assailants. The only light that was present was the one that broke through the elevator doors way above him. Through this opening, Dr Robinson and the two Changelings peered down the empty elevator shaft, admiring the wreckage at the bottom. Down below, the sound of litres of water angrily sputtering resonated off the walls.

 _She took Clara…_

The dull light that broke through the elevator doors on the fourth floor vanished. _Good, they're gone,_ The Doctor sighed with relief. He broke his white-knuckled grip on the metal rungs and began to climb upwards very slowly, taking care not to make a sound. The Timelord had successfully passed the fourth floor elevator doors before coming to a stop. He needed to remain calm and come up with a plan before continuing on.

 _Where did they take her? Perhaps I can mentally link with one of the Changelings, access the Hive mind, and found out._

He resumed his climb after isolating the one voice in his head. The choice to exit on one of the higher floors was made as they wouldn't expect him to reappear there if they assumed that he survived the fall.

 _Xeka time-travelled here... Who brought her? More importantly, how did she recognise this worn, old face?_

Chatter once again erupted inside his head. It took all of his willpower to refocus on the task at hand. Once the voices settled, the Doctor found himself adjacent to the sixth floor elevator doors. He aimed the sonic at the metal doors and opened them slightly to peer out. Towards the far end of the corridor, three Changelings shuffled about aimlessly. _If I can find an isolated Changeling without alerting it or the others, I'll be able to find Clara. There's a room close by… Let's see what's inside._

He swiftly slipped through the crack and tip-toed into the closest room, using the faulty lighting to his advantage. A handful of people lay unmoving in what appeared to be a waiting room. Treading lightly and carefully, the Doctor tried not to picture what the dark room actually looked like with proper lighting. He knew, from the many dark patches in the carpet, that it wouldn't be a pretty sight.

"If there's anyone left out there, try make your way down to the safety of the basement. We have set up a secure position down here from these… _things_ …" A familiar voice on the loudspeakers broke the unsettling silence, startling the Doctor. He stood poised, in case he had unknowingly been discovered. "Help will arrive shortly… And whatever you do, please remain calm."

 _Was that Sister Xeka? She must be rounding up survivors now…_ Her theatrical performance - that definitely gave whoever else was left alive false hope - made the Doctor's blood run cold. He crept to a small hallway lined with doors and stopped. From behind one of the closed doors was the blood-curdling sound of laboured breathing and nails being dragged upon wood. _At least something's going right today… Please, let there be only one of them…_ He begged silently. Finding the one that contained this agitated Changeling, the Doctor readied himself against the wall, then slowly cracked open the door. The Changeling drew in a sharp inhale of breath, then scurried to escape its prison. As soon as it exited, the Doctor wiggled a finger - aiming for the back of the changed human's neck. It collapsed in a heap.

"It's a good thing I remember Venusian Akido." mused the Doctor with a wicked grin. He kneeled down and gingerly placed his fingers on the temple of the unconscious being, honing in on its collective consciousness. The Doctor immediately winced in pain as a barrage of voices flooded his mind - presumably the voices of the thousands of changed people. He stumbled backwards, breaking the overwhelming connection. It took him a couple minutes to recompose himself before the crackle of the loudspeaker silenced the lingering voices his mind still held onto.

"You're a hard man to kill, Doctor. Good. In all honesty, I'd have hated to end the story there and then in that elevator."

The Doctor ran a sweaty hand through his curly grey mop of hair. "Tell me about it…"

Loud static came through for a moment, before two distinct voices could be heard: one which was muffled in the background, and one that had spoken earlier.

"Robinson could sense a foreign presence breech the Hive. Very ambitious. I suppose you wanted to see where your companion had run off to…" Sister Xeka jeered over the speaker. Grumbling and coughing fits echoed through hallways, before a raspy voice called out tenderly.

"Doctor…?"

He jumped to his feet quickly upon hearing his name. The Timelord's unique heartbeat started to pulsate in his ears as he made his way back to the main corridor. _What has Sister Xeka done to her? Her voice…_

"Doctor, Doctor, Doctor," The Cat spat in a mocking tone. More coughs and choking blared through the speakers. "She's deluded. Keeps saying you'll be coming save her. She really doesn't know, does she? She doesn't know you ruin people…"

The Doctor was now in the corridor where the elevator was. He knew that the three Changelings at the other end had spotted him, but he didn't care. Instead, his eyes scanned the walls, desperately searching for the speakers from which the Cat broadcasted her taunts. _If I can get a lock on the wave signals, I can pinpoint her transmission location,_ he thought to himself. The Changelings charged towards him. He fumbled around his pocket for the sonic upon spotting the speakers that were adjacent to the lift doors. As he scanned the overhead box, the Doctor turned his attention to the oncoming creatures. He was aware of their superhuman strength, and thought himself lucky that he had managed to get the jump on the Changeling that he had linked with. The sonic made a bleeping noise upon successfully scanning the speaker.

"Ahah! Just need to follow the trail now… Sorry fellas, can't stay and chat!" The Doctor exclaimed, running over to the fire extinguisher that hung nearby. He waited until they got close then activated the pressure vessel, sending white powder flying in their direction. The Changelings were momentarily blinded, giving the Doctor the opportunity to slip past. He held the beeping sonic in the air and followed the signal down the corridor. The screwdriver wasn't the only thing that emitted frequent beeps however, as the loudspeakers also did so faintly - albeit rather frantically.

"The dehumanisation process is slow, and since we're on a tight schedule now, we'll need to speed it up. You'll watch her burn, Doctor. Just as you happily watched my peoples' life's work burn." The Sister explained with an acidic tone. The beeping sound got much louder, almost as if the microphone was being moved closer to the source of the noise.

 _It's her heartbeat,_ he suddenly realised with sickening guilt. The Doctor had narrowly avoided a Changeling at a junction when he suddenly heard the most heart-wrenching thing in the whole universe: her screams of pain.

"NO!" he bellowed; his feet pounded at the ground harder than ever, racing to find where the trail would end. More cries came. With each that he heard, imaginary knives plunged deep into his hearts.

Sister Xeka laughed deliberately into the microphone. "Please do be still. I'm allowing quicker passage of the toxin into your bloodstream. Those cuts will heal once you've fully transformed."

The sonic had led him to the level six stairs, and upon entering, the bleak concrete stairwell was illuminated with the green glow. A pair of changed humans on the landing reeled back, clawing at their bloodshot eyes from the sudden brightness. One had lashed out in a blind rage. It sliced through the layers of clothing, tearing the skin below the Doctor's ribcage as he approached the flight of stairs leading to level seven. His hand flailed out to catch the railing, preventing himself from collapsing onto the stairs. The snarls and grunts of the Changelings forced him to continue up with one hand over his searing wound. The Doctor could feel the warm liquid trickle through his hand and down his side as he finally reached the next landing.

The seventh floor corridor was silent. Clara's screams had stopped. What had replaced it however, was something far worse. One steady, continuous beep blared. In that instant, he could feel his whole world collapse around him.

 _Clara, don't you dare…_

The speakers then promptly cut out. He was left alone in the derelict corridor. The Timelord broke out into a running limp, blinking back tears that clouded his tunnel vision. The sonic no longer provided him with a trail to follow, so he blundered down the long corridor, checking each room. He didn't know how many times he called his companion's name.

 _I only have minutes if her heart did indeed stop…_

Power tools, broken doors, and various bundled construction materials littered the floors, while the walls were either composed of wooden scaffolding or plastic sheets. If it wasn't for the sparse lighting of the construction site spotlights, he wouldn't have seen the mess around him. He also wouldn't have witnessed the shadowy figure standing at the end of the hallway. The Doctor stopped dead in his tracks when he caught sight of it, stifling a sob. He didn't have time for another confrontation, he needed to find Clara before it was too late. The shadow drifted forward, slowly being bathed in one of the spotlights that they passed. The umbra still concealed their identity, until the green glow of the Doctor's sonic revealed two partially red eyes glaring at him with unparalleled abhorrence. Words died in his mouth as he watched those once big brown eyes now pierce into his own soul.

"Clara? Clara, what has she done to you?" The Doctor croaked. He had to restrain himself from running over to her aid after his eyes drifted from her bloodshot ones to her bloody appearance. Crimson glistened, slowly running down her scathed arms.

"You didn't save me," she rasped, not taking her eyes away from his lingering ones. She took a couple steps forward, and he hastily retreated a few steps back. "Where were you?! How could you leave me like that?"

He was hit hard with a horrid flashback of their argument after Courtney's adventure to the moon. It was different this time, however. Clara took a few more menacing steps towards him while he struggled to come back to the present.

"Clara, I'm terribly sorry I let this-"

Clara pounced forward, lifting the Doctor by his neck with superhuman strength. He grasped onto her outstretched arm, feeling her pulsating green veins twitch under his touch. The Doctor's hearts twinged as he tried to avoid one of the many cuts upon her skin. She threw him into a wooden wall, causing cracks to ripple around the impact zone like lightning. Clara allowed the Doctor to slide down the wall into a sitting position, before punching him square in the jaw. He rolled to the side, following the momentum of the blow. Before she could aim a kick at his frail frame, he shuffled backwards with his elbows.

"Now Cl-Clara, you could've hit harder than that. I know you're still in there somewhere! Your eyes-" he pleaded, feeling blood pool in his mouth. She had lifted him up off the ground again before he could finish his sentence. Clara then hurled him towards the same wooden wall. Instead of rebounding off, the two-thousand year old man crashed through the barrier and tumbled into the next room. He skid to a painful stop next to a tall ladder. Broken pieces of wood were scattered around him.

Clara stepped through the shattered timber panelling. Her hands shook violently. "Because of you, I second guess myself. Everything that I do - even the most boring things - I wonder… Is this even real? Am I even still alive?" she grabbed his tattered coat from the back to drag him into a kneeling position. "Or my favourite one: have I been dreaming from the very start?"

The Doctor quickly slipped out of the coat, and by extension, out of Clara's hold. He then took refuge behind the ladder, holding it for support. His shirt was stained with dark red in multiple places. It was also ripped at his left side, exposing torn flesh _. I liked this shirt,_ he thought sadly. Clara still held his coat, clutching it tightly as if it were a child's favourite blanket. He chose this moment to try snap his friend out her deranged state.

"These past couple of hours have made me wonder that too. You see, I made a promise to you a while ago: to get you home safe. I also promised myself to honour one of the very few second chances that I've ever been granted. Both promises have been broken,"

Clara took a few forceful steps towards where he had barely held himself on the ladder. The Doctor spoke quicker when he noticed her restraint. The gleam in her red eye, where a black pupil was just barely visible, struck him with an idea.

"But I can try fix this - it's not too late. You need to take me to where Sister Xeka did this to you. I assume the changing process was interrupted, since you're only partly changed. Take me to where she left the toxin so I can analyse it, and maybe find a cure…"

The ladder was sent flying to the side, leaving the Doctor exposed once more. He lurched backwards as Clara resumed her relentless pace towards him. _I can't take another hit from her…_

"If - if this really is some twisted nightmare concocted by those nasty dream crabs… then I'm glad I got to spend these last few precious moments with you. If not - if this is real - then Clara Oswald, I failed you. And for that, I'm sorry… Sorry that I couldn't… Please…" he trailed off, unable to finish. The little strength he had left in his legs had been consumed. The Doctor sank to his knees as Clara got closer and closer. All he could do now was smile sadly at her menacing gaze, and will her to break free… or to finish him.

 _Forgive me._

The ripped jacket was tossed unceremoniously onto the ground. He felt her foot drive into his stomach; the wind was knocked out of him. The hard floor came quickly to meet his aching back. In his dazed state, he looked up at Clara's looming figure. She bent down over the Doctor's limp body only to lift his head up by the collar. The last thing he saw was the crimson tinge of her eyes as her clenched fist came rocketing towards his face...


	6. Affliction

**_Chapter 6_**

 _"Trust nothing. Accept nothing you see. Whatever happens, interrogate everything."_

 _"In case it's a lie?"_

 _"In case it's a lie."_

 _XXX_

 _"It's a pity we have to wake up, really. It's not really something we do every day, is it?"_

 _"We stay, we die, Clara."_

 _"You're always such a downer, Doctor."_

 _XXX_

The Doctor jerked awake, instantly being greeted with a throbbing pain on the left side of his head. For a second he panicked, thinking it to be that all too familiar ice-cream pain. However, the momentary blissful ignorance experienced after waking wore off. He remembered why he felt nothing but tremendous agony.

"Clara?" The Timelord called groggily. He took a deep breath in, then turned his nose up at the ghastly smell of rust. With a great amount of effort, he turned his head to properly check his surroundings. He was surprised to find himself slumped on a chair in the middle of a darkened room. His hands were placed on the armrests, where two broken leather straps hung on either side. Dried blood coated the chair's arms and the floor below it. However, when the Doctor spotted a broken cable that led to a shattered monitor, it hit him.

 _This was where Clara and Sister Xeka were…_

A stifled sob made the Doctor snap his attention to where it resonated from. There, in the far corner of the room, was a trembling Clara. She had curled up into a ball, clenching his jacket once again. Her eyes were solely focused on the grubby floor in front of her.

He shuffled to get off the chair slowly, but Clara immediately twisted her head towards him and shook it. "Don't move from the chair."

The Doctor quickly sat back down, wincing as he did. Clara's eyes still averted his worried ones, and were now glued to the chair legs.

"Why? Clara, I -"

"Just do as you're told." she whispered. He blinked rapidly, then followed her fearful gaze to the dried blood stains on the floor under the chair. _She's not going to come over here because of the blood - her blood. So, this is where she was changed_ … _she managed to bring me here_ , he realised with a pang of rage. Clara finally tore her eyes away and turned her attention to her tightening fists. She scrunched her eyes tightly shut, then rocked slightly on her heels. This went on for a few minutes, and the Doctor took this time to rest his aching body and to ponder whether he should attempt to communicate again with his slightly postal companion. However, he was struck with a frightening thought upon closer observation of Clara's look of intense concentration.

 _She must be, to a certain degree, a part of the Hive mind. Is she contacting them? Or is she trying to resist being completely consumed by their consciousness?_

"Clara, I realise that I'm probably distracting you, but I need to know… you were changed in this very spot, correct?"

She nodded; her eyes still shut. He continued, treading lightly. The last thing he wanted was to trigger another violent outburst.

"It looks like you broke free before you were completely transformed. So that changing device must still be here, yes? Where is it?" he implored. His blue eyes widened when she finally opened her eyes.

"I threw it over there," she pointed behind him with a shaky finger. He twisted around on the chair to see a miniature version of the machine that he had destroyed in the generator room. The tube above it had been broken cleanly into two, and the machine was severely dented. A small canister, still attached to the device, prompted the Doctor to grin widely. "Doctor, do whatever you're going to do quickly. I can't hold on - I can't keep them out for much longer… I'm visualising me searching for you on level six. They'll soon realise we're not there."

"Did Sister Xeka order you to finish the job - to kill me?" The Doctor suddenly inquired as he slipped out of his chair. He snuck backwards towards the machine, not taking his eyes off of the trembling shadow. While he made the audacious - but excruciating - journey to the broken machine to retrieve the canister, Clara stared off into the distance, breathing heavily.

"No. She told me to capture you." Clara replied with strained effort, then turned towards the chair to see it empty. She shot up, dropping the Crombie coat. Something heavy within the coat cluttered as it hit the floor. The Doctor turned his back to her to sprint, as fast as his damaged body would allow, towards the machine. He wrenched the canister off of the broken device, then urgently made for the chair again before she became aggressive. The gas canister was almost empty, but the amount inside was sufficient for what the Doctor planned to do with it.

 _I need to analyse this. Only then can I hope to make a cure…_

"My sonic screwdriver - it's in the coat, isn't it?" he groaned to himself. Clara stood still in the far corner. Her bloodshot eyes trailed down to where the tattered coat lay. She bent down quickly and rummaged through the breast pocket. With the sonic in hand, she stared with contempt at it. The Doctor watched in awe as her right hand, which was now functional again, shot up to her temple. The cuts on her arms had almost disappeared too. _She must've developed an advanced healing factor through the toxin. Sister Xeka wasn't lying then…_

"Arghh. I think they saw the sonic through my eyes…" Clara managed through gritted teeth.

"Let them think I abandoned it and the coat during the chase. Now, roll the screwdriver towards my chair. You don't need to come close." he encouraged softly. She lowered her right arm, and considered the request. Her eyes continued to avert his gaze - to protect him.

"Please, Clara. I can cure you."

Clara clutched the sonic tightly, huffed, and then rolled it over. It clattered loudly until it stopped within the Doctor's reach. He snatched it up, then proceeded to analyse the toxin from his seat. Clara sat back down again and resumed her pensive demeanour while the Doctor broke down the toxin into its core products.

"I've seen this before - a more advanced version, of course - but nonetheless…" The Doctor muttered as he looked at the readings on the sonic. One of the main products of the toxin was what appeared to be an organic version of blood-control used many Christmases ago _. So while the antibodies are temporarily offline, this biochemical substance infects the bloodstream - turning it green - and allowing Sister Xeka to control all who are infected,_ he concluded.

"Doctor, you're going to have to restrain me. It's like they're scratching at my brain!" Clara exclaimed, clutching the sides of her reddening face in agony. Seeing her rock back and forth, trying not to think about the pain and about his presence, put him on edge. He repaired the leather restraints with the sonic, then got off the chair.

"Take a seat."

Clara shuffled over reluctantly, not daring to look at the Doctor. She bared her teeth and hissed when she got close to him.

"Do it. Quick." she half pleaded, half snapped when she sat down. He fastened the mended leather bounds around her arms, stomach and ankles while she resisted the urge to rip apart the other side of his ribcage.

"Okay, just sit tight - no pun intended. I think I may know how to eradicate the toxin from your bloodstream." The Doctor explained. He limped over to Sister Xeka's dressing trolley that had been upturned during Clara's fit of rage when escaping. As he suspected, the equipment that lay scattered near the trolley was way beyond twenty-first century medical equipment. He flipped the trolley and replaced the tools upon it, then checked back on Clara. Her red eyes rested on the bounds that prevented her from attacking the Doctor again. She was also inhaling and exhaling frantically, trying desperately to maintain control over the rekindling fire within. He, too, had to try supress the anger he felt towards Sister Xeka and focus on the task at hand. Yanking open some of the drawers under the metal cabinet, the Doctor spotted various little vials and bottles of chemicals.

"What was she planning to do with these?" The Doctor wondered aloud, examining each compound closely. Satisfied with his inspection, he then selected a blood transfusion gun, waving it about to an imaginary audience. "My blood has these… tiny things… that will hopefully be key in stopping the main components of the toxin. I'll fiddle around with the make-up of the toxin - toss in a few of those chemicals for good measure. Then, the rest is up to you, and you're, er, recovering immune system." he motioned with his hand towards Clara, who was now growling. The Doctor pulled over the swivel chair to sit near the trolley, then sat down. He rested his left arm onto his leg, and readied the gun by selecting 'blood extraction'. The glass vial, which was attached to the gun, rapidly filled with blood as the gun penetrated the vein. Grunts of pain escaped through his gritted teeth as he quickly swapped out the vial when it was full. _Three vials should do the trick_ , he thought hopefully. By the third vial, he felt the room quiver slightly.

"Perhaps this wasn't the best of ideas, seeing as I've already lost a fair amount of blood." he mused to himself, feeling dizzier and dizzier just thinking about it. Once the third vial had filled, he pulled the gun out and proceeded to wrap the injection site with a bandage. _I really don't have time to properly treat my other wounds. They'll heal soon enough, anyway…_

"They've finished sweeping the sixth floor. The voices… I have to feed them some of my thoughts, since I've been quiet for too long. They're going to know we're on the seventh floor." Clara informed the Doctor with a quavering voice. The Timelord sat for a moment with one hand on his knee, and the other resting over the skin on his ribcage. He had to rest for a moment to avoid passing out. The clock was ticking, he knew that better than anyone. But he couldn't afford to slip out of consciousness now. _I need to make the cure - and fast!_ The Doctor took one last look at Clara, who was now as still as a rock in the chair. It was enough motivation for him to pull the metal cabinet close and begin working.

He liquefied the remaining toxin in the canister, then mixed his blood with a few other advanced chemicals that he deemed appropriate to include. Finally, the liquid toxin was fused with the mixture of blood and chemicals, producing a blue substance. The Doctor sighed sadly as he extracted a fraction of the liquid with an injection gun.

"I don't know if this will work. It may… or it may make things even worse. I'm going to administer the cure now." he told his friend with a hint of nervousness. Clara twitched at the mention of her name; her eyes still closed. The Doctor wheeled over with the swivel chair to where Clara was seated. She sniffed, then began to squirm in the hospital IV chair. He grabbed her now convulsing left arm, trying to steady it to inject her.

"Clara, you need to stay still!"

"I can't! Get away, NOW!" she screeched, allowing the horrid memory of her torture to consume her. The Doctor spotted the leather bounds on her right arm tear slightly, but continued to try calm her.

"Your affliction is what's amplifying your transformed state of mind. Think happy thoughts!" he grunted. Clara's right arm broke free, and her hand immediately found its way to his exposed neck. He gagged slightly at her tightening grip, but finally found the vein and injected her. Clara's eyes flared open when she felt the needle go in. As soon as the vial emptied, he tore away from her grip and fell backwards onto the floor. Clara jerked uncontrollably in the chair, managing to break free from the restraints. She managed a few steps towards him, before collapsing onto the ground in withering pain. Her body went into a brief spasm. The Doctor could only watch her with a sinking feeling in the pit of his stomach.

 _The person in the recovery ward also had spasms..._

He tried to delete the unthinkable by observing the colour of her eyes and veins, waiting - no, hoping - for any changes. Suddenly, she stopped shaking and closed her eyes. The Doctor scrambled over to where she now lay motionless.

"Clara? Clara! Can you hear me?" he shook her gently, then took her hand in his shivering ones. "No, no, no, no…"

The Doctor released his grip on her hand to check for a pulse on her neck. However, a hand reached out and caught his wrist. Clara's gleaming red eyes flickered open, and she finally looked right at him.

"What are you doing?" she asked him with a bewildered expression. He was too shocked to reply, and instead released her from his grasp. She sat up, now staring at his bloodied and bruised face with interest.

"What happened to your face?" Clara quipped, then stood up to dust herself off. The Doctor also got up. Keeping his distance from the calm woman, he ignored the question.

"You still have red eyes. Tell me, how do you feel?"

"Well, I - I feel alright. Are you sure they're red?"

He beckoned her over to the metal trolley, where they both looked into the reflection with the help of the green glow of the sonic. Clara only let out a small 'hmph' when two crimson circles stared back at her. She turned to see the Doctor, who was still examining his reflection, gingerly touch the bruised area of his face.

"Did I do that?" she questioned with a raised eyebrow. The Doctor gave her an incredulous look before replying.

"Do you remember anything before being captured?"

"No."

"Do you feel any sort of negative emotions at all?"

"No."

"What about the voices? Do you hear them still?"

Clara paused, strolling around the trolley and back to the seat. He assumed she was still trying to piece together what had happened after she was tortured and fed the toxin.

"Yeah. They're here all right," she muttered. She wandered around for a bit more before turning on her heel to address him again. "So, what's the plan?"

"Plan? Clara, you're still infected! The cure must've only suppressed your emotions…" he waved his hands about dramatically. "And you're still a part of the Hive mind! They're probably watching this conversation through your -"

"Don't be daft, Doctor. I'd know if they were peeping. So, plan?"

He considered her for a moment, with eyes following her as she went to pick up his tattered coat off the ground.

"You don't mind if I wear this, do you? It's awfully cold in here." Clara uttered nonchalantly.

"Go ahead. Look, I think it's time we had a proper chat with Sister Xeka." he decided. Clara slipped the jacket on and examined the gaping hole near where her hip was. Her red eyes then shot back to the Doctor.

"Good plan. I'll let them know I captured you. Like you said, best way to talk, right?"

"Right. Then, we can figure out what she's using to control the Hive mind, deactivate that, then put a stop to her. We can rework the cure later." The Doctor explained, approaching Clara with subtle caution.

She grinned widely, making him feel slightly uneasy with her piercing bloodshot gaze.

"Mission accomplished then?"

The Doctor nodded, "Let the voices in now. Let them know you have me." He raised his hands in surrender. Clara closed her eyes briefly, presumably to broadcast the image. In the far off distance, the scurrying sound of footsteps could be faintly heard.

"They want me to bring you out myself," Clara explained, walking over to grab his arm - a little too forcefully for the Doctor's liking. She noticed his apprehensive look as she began to tug on his arm. "Just go with it."

The pair exited the room, with Clara half leading, half dragging the Doctor, and navigated through the seventh floor until they were in the main corridor. A group of changelings waited, with Dr Robinson at the head of the pack.

"Ah, it's a pleasure to see you again, Doctor." Robinson jeered with a fake smile. The Doctor returned the gesture, bowing slightly.

"The pleasure's all mine, really." he spat, earning himself a jab at his torn skin. He doubled over with a cry, expecting Clara to pull him upright again. Instead, he felt two pairs of large hands shove him forward. The group made their way down the corridor to the stairwell, but when the Doctor stole a glance at his captor, he realised that it was two Changelings who had a hold on him. His companion was nowhere to be found.

They dragged him down the staircase in silence. He counted the landings that they had passed, before coming to the conclusion that they were headed back down to the basement. Sure enough, there were no more stairs to traverse down when they finally exited the stairwell. The familiar gloom of the basement opening hadn't changed, but what had changed was the presence of changed humans. They wandered about, keeping a careful eye on the group - specifically the intruder. The Doctor took note of how they all avoided the area before the tiny staircase, which, from memory, led to where the generator room, elevator, and morgue were. A metal door opened before him, and he was pushed inside.

"Hello, Doctor. Don't suppose you'd fancy a chat?" Sister Xeka said with a monotone voice. She leant over a wooden table, which had metal restraints on the corner of each end. The Doctor's eyebrows lifted upon spotting the table.

"I thought you'd never ask. Let's talk."

The Cat, with her hands clasped behind her back, sauntered over to where the angry Timelord stood. She nodded to the two Changelings beside him. They released him and backed away to position themselves at the door. The Doctor had to lower his head to glare at the Cat-Humanoid in front of him. Her lip curled upwards as she quickly brought her left arm around, aiming her weaponized gauntlet at his face. It made a hiss as anaesthetic gas engulfed him. However, the beaten man in front of her merely laughed.

"Respiratory bypass system. Nifty when exposed to undesirable gases." The Doctor patted his chest with a final snicker, then pulled the sonic screwdriver out from his trouser pocket. Before he could do or say anything else however, he felt the prick of a needle go into his bare neck. Breathing into his ear, Clara pushed the top of the syringe down.

"We know, Doctor." Clara's tender voice rung in his ear as he spun around to face her. The room kept spinning even though he locked eyes with Clara's unnerving ones. His legs became jelly as he attempted to walk towards her.

"Clara? What are you…" his voice had failed him, and he had to grab onto something to keep from falling.

Sister Xeka was now the one who was chuckling. "Put him on the table. We have much to discuss, Doctor."

* * *

 **A/N:**

Hi guys, thanks so much for the reviews, follows, and favourites! I'm very glad to see that people are enjoying the story. Uni starts up again next week, and I've almost finished the 8th chapter but haven't started the 7th yet. So what I'm saying is if I'm a bit more delayed than usual - that's why! Please keep pestering me, however, to remind me to finish this story ASAP. Thanks again. :) x


	7. Infiltration

**_Chapter 7_**

He wasn't sure how long he was strapped to the table, as he kept slipping in and out of consciousness repeatedly. There were different faces milling around him each time he blinked, but one familiar onlooker was always present. He figured the anaesthetic injected into him was definitely measured appropriately to render him harmless - but not to knock him out completely. When he properly came to, Clara called Sister Xeka into the room. The humanoid entered, looking as smug as ever, and waltzed over to a bench that was to the Doctor's right.

"Did you really think you could get the upper hand and trick me? Your companion was mine the moment she started to inhale my toxin. Although, whatever you did to Miss Oswald during your confrontation with her, it tipped her over the edge. She seems to be fully integrated into the Hive mind now. So, thank you for that Doctor." Sister Xeka explained; her voice laced with ridicule. She had her back to the Doctor, concealing whatever was on the bench in front of her.

"She did seem a little off," The Doctor admitted as he tested the metal cuffs that bound him to the table. _I just made it worse! I've lost her…_ Clara's lips pursed slightly during the conversation. She leant against the wall closest to the door, intently watching the Doctor as he finally abandoned his attempts at breaking the restraints. He then decided to continue talking. "So, I guess this is as civil as it's going to get. I have questions. I gather you do too. We both want answers. So, ladies first?"

Sister Xeka slowly spun around, revealing the contents on the bench. It was littered with various nerve-wracking instruments - including another syringe of anaesthetic. The Doctor swallowed hard as she selected a scalpel. "On second thought, may I go first? I know this is partially about revenge - emphasis on the partially. I can't help but think there's something else to all this."

The Cat came over to the table, rolling the blade handle between her thumb and index finger. The scalpel made its way to the very top button of his bloodied and torn purple shirt. Sister Xeka hooked it through the gaps of the shirt, securing the knife under the first button at the top. Goose bumps prickled his skin as he watched her pull up - causing the button to come undone.

"I'm one of the last of my kind. So, given the opportunity to both deliver justice for my people and to save Catkind, this was an offer I couldn't refuse… However, given the primitive technology and biology of the human race in the twenty-first century, it's proven… Quite difficult to replicate my kind - hence the Changelings." She explained as the second button came loose.

"Offer?"

The Cat ignored him, undoing two more buttons with the deadly instrument. "I want to be brought back to my own time to get a hold of better test subjects and technology, but the deal I made didn't include a return trip," The Doctor squirmed as she yanked off the final button, exposing his bruised chest and stomach. "Now, this leads us to my question: How do I pilot your TARDIS? I know you won't willingly take me."

The Doctor let out a low hum of amusement, "Travel agents - you can't trust them. Speaking of, did your travel agent know what I currently look like? You never told me how you recognised me."

"I've answered your first question, Doctor. Don't be greedy. You know, I wanted to turn you - just like I did with Miss Oswald - and command you to take me back. It would have been so much easier… But, you and I both know that wouldn't have worked out."

 _Because I'm not human. So if I'm immune, then why didn't the cure work?_ Sister Xeka traced the blade ever so lightly down his skin, causing him to twitch in his restraints.

"So you changed Clara in the hopes that she'd know how to operate the TARDIS? Or was it to persuade me to help you?" The Doctor scowled at the blade as it reached his stomach. He then twisted his head, searching the room for Clara. The woman was to his left, looking slightly bored as she watched the horrifying scene unfold before her. She still wore his jacket, as if it were a trophy. _Her eyes… They weren't that shade of colour before, were they?_

"Both. I was told about your companion's working knowledge of the TARDIS. However, it seems as if I've been misinformed. That, or she's somehow blocked out or deleted that crucial bit of information. Since the former cannot possibly be true, I'm inclined to believe the latter. Once I'm finished with you, I'm going to order her to walk off the roof of this hospital - and the best part is, she'd happily do it! That, or, I can think of other -"

"Shut up! Sister, she didn't need to be dragged into this. If you - "

"If it tears at the walls of your mind, screaming guilt… Or, if it pulls every one of your heartstrings - then yes, it was inevitable that she'd be a target. You lead her into your unjust world, and act as the catalyst for her undoing. Now, I'm going to ask you one last time: I can torture her or you to pluck the information from your unruly brain. You pick." she barked, clicking her fingers at Clara. She pushed off the wall and went to stand beside Sister Xeka. The Cat held out her hand, insinuating for Clara to offer her arm. Clara immediately obliged, allowing her claws to roll the coat sleeve up her arm. At the first touch of the blade on her skin, the Doctor's eyes briefly flickered to his chest, before returning back to Clara's exposed arm. Sure, she had an advanced healing factor, but he had no idea of its limits. Would Clara heal quickly if she cut too deep? These questions left as quickly as they had come. The Doctor had no intention of letting Clara come to any harm - no matter the cost, and regardless of her enhanced strength.

For the briefest of moments, he could have sworn he saw the small bump on her neck move.

"What you did to her earlier: unforgivable. Now you're thinking of laying a hand on her again - this time right in front of my eyes! You're really going to regr - "

The knife started to leave a thin line of blood. Clara clenched her teeth together and turned her head away, concealing her facial expression from both parties.

"NO! Stop! You'll do me instead!" he roared, pulling on the metal cuffs relentlessly. She released Clara's arm and shooed her away with two fingers. Specks of blood pattered onto the floor as Clara quietly returned to rest against the wall again.

"As you wish. Don't fret, Miss Oswald, we'll come back to you shortly. He's unlikely to give answers if I open him up. But, the dread he'll feel prolonging your turn while he's squirming in pain… Waiting is torture too, you know. And besides, I'm quite excited to finally see the biology of a Timelord." she waved the scalpel about as she spoke. The Cat then walked over to where the Doctor lay seething. His chest rose and fell erratically. She wiped off the smear of crimson on her scrubs.

"If you make one mistake - and I die - then there's no ride home." The Doctor bluffed as she decided where to make her first incision. Xeka opted for his lower abdomen, and had the blade hover over the skin, causing him to tense. _I need to keep her attention solely on me for as long as I can…_

The Cat snorted, "If you die, she dies quicker. Face your punishment with courage!" The Doctor shot one last look at Clara. She had seized the skin over her cut, clutching it a little bit too tightly. _Clara, look away_ , he silently mouthed at her. "Shall we begin?"

He writhed in irritation as beads of blood trailed behind the knife. Out of the corner of his eye, he saw the short brunette gulp more visibly. Sister Xeka unexpectedly applied more pressure, causing him to cry out and slam the back of his head against the wooden table. It took all of his willpower to not arch his back and not to jerk about violently. The wood creaked as he continued to thump his head. Every muscle in his body was taut. The metal cuffs that bound him dug into his wrists and ankles as he pulled on them. A sharp intake of breath however, made the knife stop.

"Sister, we have a problem. One of the Changelings spotted a squadron of police officers enter the complex via the carpark." Clara blurted out. Her voice was slightly higher and less raspier than it normally would have with the toxin. The Doctor watched her eyes deflate as Sister Xeka pulled the metal knife from the wound she had inflicted. _Oh no…_

"What? I thought we sealed the carpark in anticipation of human interference from outside?" Sister Xeka queried. Her mouth hung slightly open long after she'd finished speaking.

Robinson stepped out of the shadows of the far corner of the room, his arms folded. He huffed in frustration, "I saw it too, we need to deal with this quickly before it gets out of hand."

"Ambush the officers. I'll convert them, then they can report back with a false alarm." Sister Xeka ordered as she stood up. Tossing the bloody scalpel onto the bench, she made her way towards the door.

"You don't have another machine to do so, Sister." Robinson reminded her after relaying the information to the Hive. He went to follow her, but she held up a finger, stopping him in his tracks.

"Stay here with Miss Oswald and the Doctor. Make sure neither of them move. I'm going to prepare small canisters of the toxin for my gauntlet - it should be enough to start the transformation. I'll be back shortly." she said, then disappeared outside, slamming the door on the Changeling leader. Dr Robinson did not move from where the Sister stopped him. _He must be making orders mentally. Wait, what is that..?_

Barely concealed by his thin black hair, a small metal chip protruded at the back of his head. The Doctor lost sight of it however, when the postal man spun around and made his way towards him.

"Don't think yourself lucky, Doctor. In fact…"

Robinson turned his attention to Clara, who now had her eyes screwed tightly shut.

"Miss Oswald, grab the scalpel from the bench. I'd like you to do the honours." he smiled wickedly. Clara hesitantly opened her eyelids, then strolled over to the bench. She stood there for a moment, as if contemplating, before Robinson snapped.

"Miss Oswald. Grab. The. Knife."

The sound of metal clunking together and scrapping the bench echoed throughout the room. Clara turned back around, now wielding the blade with her right hand. Her left was stiffly by her side. The Doctor spotted the mess she made on the bench, but noticed that something else was missing…

"Now, continue where the good Sister left off," Robinson pointed to the Doctor's lower abdomen. Blood was slowly gushing out of the deeper cut. "Continue upwards, applying more pressure as you go."

The red eyed woman stood next to Dr Robinson. They both leaned over the helpless Timelord. She readied the blade. He looked up at her, feeling his heart slam into his chest. Clara's eyes darted to his.

"Do it!"

"With pleasure," Clara muttered. She swung her left arm at Dr Robinson, injecting him in the neck with an anaesthetic shot. "No one controls me, except for me. Got it?"

He tried to shove Clara off, but her strength was just on par with his. Growls and hissing erupted from the deranged man as he staggered to the ground, yanking out the needle haphazardly. The tattered jacket that Clara wore was grasped at by the grovelling Robinson, before he collapsed onto the ground unconscious.

"Not a control freak, eh?" The Doctor breathed with a small chuckle as she rushed over to him.

"You, mister, are in no position to make wisecracks!"

"Yes, boss."

"All jokes aside, Doctor, I am so very sorry… I can't even begin to explain… I couldn't let you know what I was doing. The Hive would've caught wind of it easily if I verbally told you. Oh, and don't get me started on trying not to think! They probed my brain. They heard my thoughts, Doctor. They still can right now…" her voice faltered when she laid eyes on the gash across his stomach. She held back a few sobs, before profusely apologising again.

The Doctor frowned. "Clara, no, no, no! There's nothing to apologise for. I should be the one apologising! I - "

"I couldn't let her do it, I had to do something."

"Hey, it all worked out, right? You came in at just the right time." he comforted her. She'd probably never forgive herself for what had transpired these past couple of hours. He understood the feeling, as he wouldn't forgive himself either for dragging her unwillingly into this. Once she recomposed herself, she ripped open the metal cuffs at each end of the table, freeing the Doctor. He grimaced as he tried to sit up. Clara put a hand on his chest.

"Don't get up just yet. There must be bandages around here somewhere. We're definitely going to talk about this later, okay? Right now, we've got to fix you up and stop Sister Xeka. I don't know how much time I bought with the police story." she explained as she hurried over to scour the bench and drawers for a bandage roll.

"So the police aren't here then?" The Doctor said with a sigh of relief. There was already a lot of blood on his hands today. There was no need for any more innocents to get caught in the crossfire of Sister Xeka's madness.

"No, I imagined it. Good thing I have an exceptional imagination. Being an English teacher helps too." she smirked, coming back with the bandages. The Timelord raised his eyebrows, clearly impressed with his companion's improvisation. Clara quickly covered the gash on his stomach and the torn flesh above his ribcage by wrapping the bandage around him.

"Thank you, Clara. Don't worry, it'll heal sooner than you think." he reassured her. Sliding carefully off the bench, he rebuttoned the purple shirt.

"So, infiltration was step one. I honestly didn't think I'd get past step one."

"We can improvise some more," the Doctor pointed at the electrical chip on unconscious Dr Robinson. "I think that's how Sister Xeka has been controlling the Changelings. Destroy that, and I assume we'd take away her servants."

Clara pulled out the sonic screwdriver from the pocket of his coat and handed it to the Doctor. The sonic made a squeal when it activated, causing the chip to fizzle and produce a puff of smoke.

"Well, that makes our job a lot easier. Oh, one of the Changelings just saw Xeka head down that tiny flight of stairs to the sub-level - where the elevator is. The one who was with her didn't follow her down, so she's alone. Also, if you're looking for more things to 'improvise' with…" Clara dug into the coat pockets once more, showcasing a small cylinder of blue liquid. "Nicked it while you were being led to the 'dungeon'."

"The cure? Oh, Clara!" He waved his hands about excitedly. "Since it's obviously working on you, we can revert these people back too!" he hobbled over to examine how much of the cure was left. It was almost filled to the brim - as he hadn't needed to use much on Clara.

"How?"

It was now the Doctor's turn to grin widely, "We fix the machine that was attached to the generator, atomise the cure, replace the toxin with said cure, and then disperse it! Simple!"

"If you say s - Urghhh." Clara put a shaky right hand on her forehead.

"Are you okay?"

"Yeah, it's just that I can still hear their voices - although it's a lot less loud now, thankfully."

The Doctor peered into her eyes with his strained ones. The red colouring had become a lot darker, and the green veins on the sclera had discoloured greatly. Her pupils were also clearly visible now. _She's probably losing her strength too,_ he guessed.

"Give it time, they'll be gone soon. C'mon, let's head to the generator room - I gather we don't have much time." The Doctor beckoned, cradling his bandaged stomach. Clara nodded, then pulled the black coat off. She offered it to him, feeling a pang of guilt when she properly saw the state of his battered shirt. The bloodied bandages were visible through the holes in the lower half of the purple material.

"We'll be running shortly anyway. I'll be warm."

He gave her a quick smile as he took it, slipping on the warm jacket. The two then headed for the exit, unsure of what to expect outside the metal door…


	8. Liberation

**_Chapter 8_**

The horde of Changelings, who previously gave the Time Lord menacing stares when he passed through beforehand, now huddled in small groups in the dim room. Here and there, one would wander around to another group. All had the same expression: Lost and confused. Clara and the Doctor, not wanting to tempt fate any further, slipped quietly by them to the small flight of stairs. Clara had made it to the stairs first and descended. She heard a sploshing sound, and felt her foot submerge into something cold. Pulling her foot quickly out of the water, she stood idly on the step that wasn't engulfed in the dark water.

"Doctor, there's water everywhere! When did this happen?" Clara exclaimed as the Doctor joined her on the step. He gave her a puzzled look as he tested the water's depth. She watched him descend rest of the inundated stairs until the murky liquid reached his knees.

"It stops here. Hmm, I wonder…"

"It wasn't like this a couple hours ago." Clara uttered as she hesitantly followed him into the icy water.

The Doctor tapped his chin, peering down the dark corridor. The low lighting caused the walls to reflect the glistening water, creating wobbly glowing patterns where the still water had been disturbed. Clara began to shiver, so decided to wade forward.

"The elevator crashing must have had something to do with this." the Doctor concluded, recalling the spray of water he heard while inside the shaft. He then followed after Clara, aware of the growing sensation of not being alone in these flooded hallways. Water lapped at their thighs, and the only sound they heard was the sloshing of the grotty liquid around them.

The pair passed a junction, when the Doctor held out a hand suddenly - bringing them to a halt. He put a finger to his lips, then pointed down the corridor. Clara strained her ears, blocking out the low hum of the Hive mind. All she could hear was the settling water and a distant scraping.

"Is she still down here?" Clara whispered in his ear - for fear of being heard.

"I'm not entirely sure yet. She would have definitely obtained the canisters of toxin by now."

They started up again, being more careful now with the sound they generated. Rounding the bend and seeing the elevator doors down the corridor eased Clara's racing thoughts. _One of these doors leads to the generator room_ … _Now, which one was it?_ They waded up to a room, cracked the door ajar and peered inside. A disheartening thought struck Clara upon seeing the dark room as flooded as the hallways they trekked through. She tugged on his jacket, and he swooped down to listen to her lowered voice.

"What if the generator room is flooded? Will we still be able to turn it on?"

Before the Doctor could reply, a booming voice resonated through the corridor.

"No one is turning the generator on," Sister Xeka screeched, hidden somewhere in the maze of corridors and rooms. The Doctor scanned his shadowy surroundings, trying to pinpoint her rough whereabouts. "Robinson isn't picking up on his com, so I assume you two dispatched him. Tsk tsk."

The unmistakable sound of metal scratching the walls and copper piping made Clara's blood run cold. The voices of the Hive mind grew noisier, causing her to double over in pain. The Doctor knelt down to where she was crouched, and put an arm around her. He continued to frantically check each doorway, and glanced up and down the length of the corridor.

The Cat's incredulous tone rang again. "How did you manage to withstand my toxin, Miss Oswald? Even in your almost completely transformed state, you still managed to restrain yourself. You could've inflicted damage beyond repair when you confronted him on level seven. But you resisted orders… How?"

Clara fought both her resurfacing mental anguish and the Hive's assault, managing a short, but simple answer.

"I'd never hurt him."

 _Clara raised her fist again to aim another blow at his face. His head had lolled backwards - clearly unconscious. She still had the urge to keep hitting him, regardless._

 _"I would never, ever, give up the Doctor, because he is my best friend, too. He is the closest person to me in this whole world. He is the man I will always forgive, always trust. The one man I would never, ever lie to."_

 _She stopped mid-swing, staring in bewilderment at the man before her. Her own words echoed in her head, drowning out the hellish voices who urged her on. Blood dripped from his gaping mouth down his chin._

 _"What am I doing?"_

A loud, scornful laugh was the response that came from the sinister Xeka. "Yes, yes. Robinson told me about your lingering thoughts. Your deluded and misplaced belief in him only makes you a martyr - a dead woman, to put it in better words. It's still not a good expl-"

"Don't listen to her. She knows she's been beaten - and she's desperate now. We need to get to the generator room and cure these people before she or Robinson repair the control chip." the Doctor pressed, trying to ignore the Cat's disdainful remarks. Sister Xeka continued talking as the two stood up, now soaked to their waists.

"Doctor, I can handle her. You're the brains, and I'm currently the receding brawn. Go fix the generator and do what you have to do. I'll do the distracting." she explained under her breath. Clara went to head into a room where she thought the Cat's speech had generated from. The fact that her voice bounced off the walls didn't help at all. Before she got any further, the Doctor grabbed her arm.

"No! Clara, I won't let any more harm come to you. If she wants a fight, she'll see me in the generator room."

Clara swung back around to face him. The sorrow in his eyes only added fuel to the raging fire within her. Whether it was the disintegrating toxin talking or her, she really didn't know anymore. Only one thing mattered: Sister Xeka paying dearly for the horrors of the night.

"You and I both know that's not a good idea. You're in no state for any physical confrontation. I'm still strong-ish. Look, I'll be okay, Doctor. Just… go. You _can_ get the generator to work again, right?" Clara asked. He paused, mulling the straightforward plan over in his head with a frown.

"If I can override the circuit breaker, then we'll have power," he explained, then let out a small sigh of defeat. "I'll let you know when I turn the electricity on." Clara gave him a warm smile, prompting him to add "Be careful.".

"I'll be fine. You stay safe too, okay?" she whispered, then gave him the gentlest of hugs. Right now, she didn't mind that his sticky bandages clung to her singlet. She didn't care that she couldn't feel her legs. Just him being here was comfort enough for her, even if he didn't return her hugs. The numbness from the cold water instantly faded away however, when she felt his arms return the embrace. The instant it happened, her eyes bugged out of her head. She could've argued that it was the most surprising thing to happen to her tonight. Clara was sure she could feel his arms now wrap tightly around her back. _Is he - is he hugging me back?_ She grinned into his chest. They released each other, and the Doctor gave her a squeeze on the shoulder and an encouraging nod. Parting ways, Clara headed to make an obnoxiously loud racket in the hallway, and the Doctor staggered to the generator room with the cure.

Clara made sure she kicked around as much water as she could in the corridor, before allowing a moment to listen to see if Sister Xeka was approaching. She sloshed to the entrance of the generator room, hearing the familiar buzz of the sonic screwdriver at work. _I guess I can just stand guard here instead if she doesn't want to play,_ Clara thought as she positioned herself under the doorframe. A zap and a cry of pain emanated from within the room, causing Clara to turn her back on the corridor. She was about to enter the small room that led to the hidden generator room when the sound of water splashing erupted. An overwhelming force yanked her from behind, dragging her out into the corridor. She was thrown abruptly into an adjacent wooden door, crashing through it and sinking into the pit of icy, black liquid within the room. Clara remerged, trying to regain the air that had been knocked out of her. Sister Xeka opened the broken door and stepped into the room. Her lips twisted into a wicked grin as she pounced over to where Clara was sitting. Clara sunk back and disappeared under the water, swimming out of the way of the predator's lunge.

 _Even if she can't see me down here, I don't know how long I can hide for…_

Laying still, Clara couldn't hear or see any disturbances to her watery surroundings.

 _She's waiting for me to resurface,_ Clara thought bitterly.

Excited murmurs of multiple voices blasted in her head, catching her off guard. Clara gasped, releasing a series of bubbles upwards. Her hand automatically went to her mouth to stop any more air bubbles from escaping. The world stopped around her. A few moments passed, to which Clara felt a tightness in her lungs.

 _I can't wait dow-_

Claws plunged into the water above her, digging into her arms and ripping her up and out of the serenity of the water.

"I'm happy to play a game of cat and mouse with you, if that's how you want to spend your last moments." Sister Xeka jeered, before tossing her across the room like a ragdoll. Clara landed in the water once more, and scrambled backwards upon seeing the enraged Cat approach her.

"Give it up, Xeka. You've got no one left to help you."

"You think the liberation of these disgusting, petty humans in this hospital has stopped me? No. Quite the contrary. It's made me even more determined. I'll find a more appropriate time period and return, ensuring their permanent cooperation."

Towering over Clara, the grey Cat reached down to take hold of the brunette again. This time, Clara was on the offense. Given the opening, she used both feet to kick Sister Xeka in the stomach, propelling her backwards. Clara then bounced up to follow through with a tackle, but Xeka had already recovered. Before she could stop herself, Clara charged straight into the humanoid's raised gauntlet - and into a mist of unknown chemicals. Momentarily dazed, Clara collapsed into the icy water. The voices of the Hive mind grew slightly more prominent, tearing once more at the walls she had put up in an effort to conceal important information.

"W-what did you do to me?"

Sister Xeka chuckled, watching Clara in her temporary encumbrance. With wobbly knees, she managed to stand. Spotting a metal table to her right, she waded over to it for support. Xeka's green slits followed her every move carefully, anticipating her prey's next move. Realising it was an opportunity to finish her and move onto the Doctor, Sister Xeka sauntered over to where Clara kept herself steady.

 _I need to keep away from her and that gas. Another whiff of that stuff and I'm surely done for…_

Clara trudged quickly around the old rusty table, dodging the vicious swipes of the scalpel. This went on for a few moments, with Clara rushing around the table one way, then changing directions to counter Sister Xeka's attempts at reaching her. Their eyes never left each other, with each watching each other's moves carefully. Finally, Clara froze when her opponent froze. Judging by the Cat's visage of pure abhorrence, it now seemed as if she was done playing chicken. The corner of Clara's right lip curled upwards in a smug grin. The more she taunted her, causing Xeka to make mistakes, the more time she bought the Doctor. Without a second's hesitation, Sister Xeka lunged across the table, colliding with Clara and submerging her into the grimy water. After a few precious seconds without oxygen, Clara resurfaced with Xeka. Realising she was still lacking air, she clawed at the Cat's furry arm in an attempt to remove the hand around her throat. Clara cursed inwardly at the fact that her superhuman strength had disintegrated considerably with the continued effects of the cure.

"No more games. I have enough toxin in here to change you back, plus, a little something extra that can't as easily be cured. This will convince your precious Doctor…" Sister Xeka spat, forcing Clara to a kneeling position. Through her ungracious chokes and gasps, Clara supressed a laugh by snorting. "What's so funny?" the Cat asked innocently. By being forced to look up to her attacker's menacing figure, Clara noticed the overhanging copper pipes.

"I'm n-not turning b-back into that - that _thing_ again," Clara managed through her gags for air. Xeka brought up her left arm, which had the weaponised aerosol toxin fixated to it, to gas her again. This time, it would be more than just a whiff.

"Clara?" The Doctor called from the adjacent room. From the anxious tone of his voice, Clara guessed that he had managed to prepare the cure and fix the generator and dispersing machine. He was now waiting for her to get to safety. In the Sister's split second hesitation upon hearing the Doctor, Clara snatched her left arm. Pulling her closer in, she proceeded to kick Sister Xeka square in the stomach. Recoiling back and stumbling down into the water once more, the Cat released Clara's throat. Clara then followed through with the momentum of the kick and brought the cat's left arm to her face - which was painted with agony. The scene was reversed now; Clara had the Sister kneeling before her.

"You've lost Xeka," Clara said through gritted teeth. Sister Xeka looked up and met her gaze with equal fury. Clara continued, "Last chance, who sent you back to this time period?"

"You'll know soon enough, Clara Oswald."

Clara knew she wasn't going to get an answer, so she jerked the Sister's wrist upwards to activate the device. A jet of gas flew out of the device, slithering its way into Sister Xeka's airways. Clara let go of her wrist and leapt upwards. She grabbed onto the pipes and swung her legs up to secure herself. The Cat thrashed about in the water, hissing and lashing out blindly in front of her.

"How dare-"

"DOCTOR, NOW!" Clara yelled. With her words, the generator whirred to life. Along with the sounds of the air ventilation device, the noise of machinery and electricity echoed and buzzed throughout the basement, ringing deafeningly in Clara's ears. With this, the sound of screaming pierced the air. It crescendoed quickly, overcoming the combined racket that the electricity and machinery made. Clara twisted her head down to see Sister Xeka below. Her face was contorted. She twisted and flailed about as if she were being pulled in every direction by invisible strings. It suddenly dawned on Clara what she was witnessing. Electrocution. A deadly room laced with electrified water - and she was in it. Clara closed her eyes quickly. She didn't want this seared into her memory, nor did she want to dwell on what would happen if she let go of the pipes. On closing her eyes, she felt dizzy yet again. _No, not now. Please, not now._ She clung tightly to the pipes with white knuckles. The adrenaline that surged through her earlier had now faded. Instead, fear made its way in to fill the void.

"Doctor! How long will the generator run for before the cure has been spread?" She called out, her voice shaking uncontrollably. She waited. No reply.

 _What if he didn't make it out of the water? No..._

She shook the thought off, and instead, focused on the echoing voices of the Hive that now flooded her mind. A flurry of confusion, anger and despair were all Clara picked up on, as the voices continued to fade and become disjointed due to the cure's prolonged progress. On top of that, the superhuman strength that Clara had possessed was on the brink of disappearing. Through her dazed state, she felt the little voices gnaw at her head. One voice was stronger than the rest, almost reassuring - encouraging even.

 _Let go._

 _Take the plunge, it'll be okay._

 _How long have you been holding on for?_

Her right arm started to throb and her back ached. That was probably a good indication. Clara opened her eyes briefly, only to see the pipes above her spinning rapidly. It was unbearable.

 _Maybe it's time to let go, Clara._ It was her own voice now beckoning.

The pipes that her legs were crossed over felt like knives digging into her. She could feel her dead weight, dragging her down lower and lower off of the pipes. Her fingers slowly slipped, loosening her grip. Closing her eyes, she allowed her tired limbs to give way and let go…

* * *

 **A/N:**

So I decided to split the last chapter up into two parts since it was pretty long. So more cliff-hangers! Expect the next chapter up within the next couple of days. Thanks to all who've reviewed, favourited and followed this story so far! Not long now till the conclusion :) x


	9. Absolution

_**Chapter 9**_

Both cold and warmth engulfed her simultaneously. Clara felt herself crash into something solid. Rough hands grabbed onto her shoulders. The water settled around her, and all she could hear was laboured breathing. Shocked that she hadn't experienced electricity flow through her body the moment she hit the liquid, Clara finally opened her weary, brownish eyes. The steel blue eyes of The Doctor greeted her. The Time Lord had broken her fall by catching her and stumbling into the icy water. He was now cradling her, eyes wide with confusion and distress.

"Clara, are you alright?" The Doctor asked as he lifted her back slightly to ensure that most of her upper body was out of the water. His legs were numb from the cold, but he didn't mind if he knelt there for just a few more minutes.

"Doctor? How? I…" She trailed off, still reeling from her dizzy episode.

 _He's alright. He's okay,_ Clara told herself repeatedly.

"I called out, saying it was safe to be in the water again. When you didn't reply, I thought the worst…" He stopped, obviously trying to supress the panic that he had experienced. The Doctor helped her up onto her feet. He quickly steadied the dizzy brunette by grasping her shoulders. Had he been any later, she would have fallen back down again.

"That's like the third time today you've assumed that." Clara joked. Her knees wobbled violently, even under the Doctor's support. "Hey, I - I don't think I can walk just yet." She muttered while shivering. Bringing her aching arms up and folding them across her chest, she looked up at the Doctor, who still held his look of concern.

"We need to get out of the water before we catch a cold. Heading to a safe place would also be a good idea - in case the cure doesn't have an immediate effect on the Changelings." he explained. At that, he scooped Clara up, taking her by surprise. She wanted to say something, but found that she had no energy left anymore. Instead, she let her eyes droop as he waded out of the generator room. By the time they reached the corridor outside, the Doctor felt Clara's arm slip off his shoulder. He looked down to see that his companion had gone limp in his arms.

XXX

The crackle from a loudspeaker startled Clara out of her near comatose state. Hospital personnel over the coms relayed information and were directing the general public. It was all gibberish to her, as her mind refused to process anything. However, it was reassuring to know that the cure had indeed worked on the rest of the people of the hospital. Clara suddenly realised that she felt a great deal warmer than she had been when she'd closed her eyes, and peered down to see herself in the Doctor's tattered coat once more. Out of the corner of her eye, she could see the familiar purple shirt of the Time Lord. She craned her sore neck to look at him directly, noticing that they were both leaning, side by side, against the cool brick wall of an unfamiliar room.

"Ah, wakey wakey! Just in time too, the backup generator seems to be operational again. And, uh, sorry - this was as far as the adrenaline would take us. Thought I'd sit and allow the both of us to heal and rest up." The Doctor declared in a casual manner. Clara studied her surroundings in the dimly lit room. A familiar musty odour filled her nostrils.

"We're still in the basement, aren't we?" Clara said, clearly amused at the Doctor's valiant efforts.

"Yes. Near the stairwell. Actually, there's a few good reasons why we didn't go up. Wasn't just because of my frail state."

"My hero."

"Oh ha ha. Very funny," The Doctor mumbled sarcastically, giving her a dirty look. He stood up from his crouching position and offered his hand to her. "How are you feeling, by the way?". Clara regarded his hand, then took it with a smile. He pulled her up effortlessly. Unlike her, Clara figured he'd healed mostly while they rested, which was somewhat of a relief. Sadly, she knew that the deep slice on his stomach would remain for a couple days. It would be a harrowing reminder of what the two went through - specifically, what she had done to him during her time as a Changeling. Clara resolved to seek absolution once they were aboard the TARDIS and away from this hospital.

"Aching all over. Headache. A bit cold. What about you? It looks like the minor stuff has healed, but…" she couldn't bring herself to mention the gash on his torso.

The Doctor sighed, "Well I'd have hoped that my jacket and a bit of body warmth would have helped. Oh well, the flight of stairs up to the roof will certainly fix that. And I'm fine. Sticks and stones, Clara."

"I don't think that's how you'd use the phrase."

He headed for the door, with Clara on his heels. She suddenly paused. Trying to concentrate and pushing past her temple's dull pain, she searched for the voices. Her mind was once again hers and hers alone, thankfully.

"Doctor, the voices are gone. What colour are my eyes?" she asked, making an effort to conceal her joy. She needed to be sure that she was completely cured before she could celebrate. The Doctor lingered at the door for a moment, before closing the gap between them in a couple of long strides. He placed a hand gingerly onto the side of her head and peered into her eyes, searching for any sign of the blood red that bore into his eyes only an hour or so ago. Satisfied with what he saw, his hand dropped from her face.

"No trace of the toxin left. They're as brown and as large as they've ever been." he said reassuringly. He turned on his heel and started for the exit. They made their way to the stairwell in silence, before the Doctor jumped suddenly.

"What's wrong? Forget something?"

"There's still more of the toxin canisters down here, I'm sure of it. Stupid, stupid me!" the Doctor exclaimed and rushed back to the flooded section of the basement. _Good,_ Clara thought nimbly, _I hope he destroys every last bit of that nasty stuff._

"If that's alright with you, I think I'll wait here." Clara called after him as he disappeared down the small flight of steps. She shuddered at the thought of the Time Lord going back through the icy water, and pulled his coat more tightly around herself. A few minutes passed before she heard frantic, but faint, splashes of water. The Doctor reappeared, bearing a scowl on his face.

"They're gone." He growled.

"What?"

"The canisters. Gone. Our feline friend has also disappeared into thin air."

"No, that's not possible. A shock like that would have surely killed her. She's dead! Maybe someone else was down here with us and moved her?" Clara suggested, her heart sinking to her stomach at word of his discovery. She didn't want anyone else to go through what had happened today, let alone face Sister Xeka again - if she was still alive that is. Sure, the rage she felt towards the Cat Humanoid was still fresh, but it didn't course through her veins as it did when she was still under the influence of the toxin.

 _I can't fight her again… Not like that._

The Doctor breathed heavily, kicking himself for not thinking to check earlier. Clara figured his distress would resurface again, so went over to grab hold of his arm.

"Clara, everyone's still in peril…"

"Another day, Doctor. Right now, we should focus on rest." Clara sighed. "And besides, we know how to beat the toxin. That's got to be worth something, right?"

"Oh, whoever's calling the shots will change the formula. They may even perfect it too. Today was all for nothing!"

"We'll find them, Doctor. We will. And we will put a stop to them." Clara said with newfound determination.

XXX

Clara inhaled deeply under the cloudless night sky. The smell of fresh air on the roof of the hospital was exhilarating to her burning lungs. Having such a simple commodity withheld from her, and instead being treated to various toxins and ghastly scents, would have driven her mad had it gone on for any longer. Luckily, the pair made it out in one piece. Keeping that in mind, the Doctor and Clara staggered on. The darkened path to the TARDIS had been illuminated with the calming green light of the sonic. They both came to a halt at the doors, clearly exhausted.

"I don't like it - not knowing who sent Sister Xeka. Not knowing things bothers me. Whoever sent her must have been down there with us when Xeka's body disappeared." the Doctor said between puffs of breath as he unlocked the doors. Clara was surprised his mind was still in overdrive after today's events, although she should've known that he would pick at the only loose end left in the mystery.

"Yeah. Although, I may have some idea as to who it could be… As for Sister Xeka and her elusive friend, they're somewhere. They can't have gone far." Clara offered. She slowly, but carefully, walked over to the ledge nearby, squinting to speed up the process of her eyes adjusting to the city lights. The view of London at night was always stunning, and she was grateful to be able to gaze upon it once more. Clara cradled her now mended right arm. It still ached, but at least it was now functional again. She didn't want to admit it to the Doctor, but secretly she was thankful of the dosage of the toxin - only for the healing factor and heightened strength - nothing else. The Doctor appeared by her side, following her gaze to the bright little beacons of light that littered the scenery. They stared for a while, searching. Neither wanting to admit defeat. The thought of Sister Xeka and her benefactor still at large sent shivers down Clara's spine.

"I'm afraid that somewhere has, perhaps, turned into a 'somewhen'. There's nothing we can do now - only wait." The Doctor finally said dejectedly. He glanced quickly down at Clara, spotting her pointed look.

"We really need to come up with a better word than 'somewhen', you know" she poked, attempting to lighten the mood.

"Agreed," The Doctor grinned, returning the light-hearted gesture. He nodded his head in the direction of the TARDIS, motioning for them to leave. "Although I'd like to see you try to do better, Teach.". Clara only chuckled in response. She wandered with the man back towards the blue police box.

Clara paused before the doors. "Listen, did you want to… uh…"

"Have that conversation?"

"Well, I was going to say get your wounds properly treated before we leave. But, I would like to have both conversations sometime soon. The one about today and the one about Christmas, please."

The Doctor smiled down at her, holding the TARDIS doors open.

"I'm not sticking around here. Last time I was treated at a hospital, it didn't go so well. Don't worry, it's nothing a trip to the medical bay won't fix. C'mon, in you come! We'll talk over coffee. I know a place - "

" _After_ we get you fixed up, alright?"

He snorted, ushering her through the blue doors. "Yes, boss."

~~~END~~~

* * *

 **A/N:**

 _Fin._ Thank you all so much for reading this story! This was loads of fun to write and has definitely got me excited to do more! I absolutely cannot wait for series 9! Speaking of, I plan to do a sequel to this as I have ideas (expect an epilogue maybe...?). But that won't be for a few weeks at least. Mainly, it's because of University and because I want to get a feel for the new season. I also want to see where the Doctor and Clara are in terms of dynamics, so to speak. To everyone who reviewed, favourite and followed this story - it really put a smile on my face! So a special thank you is in order. Please, if there's anything to be said about my style of writing, storytelling, development of characters etc. then leave a comment! I'd love feedback for my next story. Stay tuned for their next adventure - I'll post the epilogue here to indicate my start when it happens. Thanks again :) xx


	10. Epilogue - Encryption

**_Epilogue_**

The low hum of the TARDIS console was the only sound accompanying the occupants inside. The Doctor rested in his armchair on the upper level of the console room. His eyelids refused to open. Below, Clara sat restlessly on one of the bottom steps leading to the lower floor. After a visit to the TARDIS medbay - and a change of clothes and bandages - the pair both returned to the console room. Exhaustion had finally hit them, so the Doctor moved the TARDIS to Clara's flat. Neither, however, managed to exit the blue box. Clara's resurfacing guilt had instead driven her to the lower level to gather her thoughts. _What could I possibly say to the man I physically hurt? The man who returned, and asked to stay with me even when I was grieving?_ The humming of the TARDIS grew louder with the voice in her head. _I could have fought back harder. I could have stopped his interrogation earlier if -_

"Clara, you do know the TARDIS picks up on your distress?" The Doctor called wearily. Clara let out an awkward chuckle.

"Yeah, I kinda forgot. Sorry."

"Come upstairs," He suddenly said. She could hear the chair creak, followed by a grunt. The sound of boots on metal then echoed throughout the interior. Clara slowly got up and ascended the stairs to find that the Doctor had come down to fiddle with the controls. He leant on the console panel for support as Clara approached him. Upon seeing this, she stopped in her tracks, deciding not to come too close. The treatment the medbay offered could only do so much to help the injured Time Lord. "So which one is bothering you more at this very moment? The events of today? Or Christmas?"

"Today. Look, Doctor, I - I'll just start with the worst offence. I'm sorry I didn't stop your interrogation sooner -" she began but he swiftly cut her off.

"Do you think I'm bothered about that? I'm just annoyed that Sister Xeka managed to give us the slip. And besides, you did what you had to do to keep up the pretence that you were still infected. Our escape couldn't have gone any smoother than it did." explained the Doctor. He frowned however when he saw Clara shake her head.

"Please, just let me finish. I'm also sorry for hurting you at - "

"You weren't even yourself. Clara, this is unnecessary. You don't need to apologise for things that were out of your control. If anything, I should apologise for letting you get captured in the first place."

"No, like you said: no control. My issue is… I - I'd never hurt you, okay? And then I let it happen… and, and I never want it to again," Clara blurted, "and as much as it pains me to say it, I'm hoping that those dream crabs still have me. You know, this is all…" her voice strained. The Doctor understood now, and watched her intently as she stared at her boots with a pained look. He edged around the centrepiece of the console room, stopping only inches away from her. Clara tried to shy away, but he grabbed her arm. Her voice failed as he held her gaze.

"I forgive you." he said softly. There were so many things he wanted to say to her in that moment, but perhaps this is what she needed to hear right now. He made a mental note to bring up Christmas and the dream crabs at a later time. Tears started to well up in her eyes. As she was about to pull him in for an embrace, the familiar cloister bells began to ring throughout the TARDIS, startling the pair. The Doctor spun around, racing over to a monitor. Clara took her position next to him, studying both his features and the monitor. The change of expression from confusion to horror told her all she needed to know. They were in danger, yet again. She drew closer to the screen. Amongst the lines and lines of code and Gallifreyan symbols, an encryption flashed. The words rearranged hastily. It now read:

 **SCHRODINGER PROTOCOL INITIATED**

* * *

 **A/N:**

*Cue title sequence* Hey guys sorry for the massive delay! This little snippet serves also as the prologue to my new fic that has been cooking for the past 8 months. The story is set but I just have to write it now! Expect longer times between chapters too since Uni has started up again. Thanks again to everyone who has read the series, and has kept this story on tab.

 ******UPDATE******

The link to the sequel 'We Happy Few' is now up! Just copy paste the link in front of the usual fanfiction url. Sorry I don't know how to properly link the story in!

s/11847954/1/


End file.
